806191593614475264
806,191,593,614,475,264 is an even composite number composed of four prime numbers multiplied together.
806191593614475264 is an even composite number. It is composed of four distinct prime numbers multiplied together. It has a total of one thousand, nine hundred divisors.
Prime factorization of 806191593614475264:
218 × 34 × 74 × 2513
(2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 × 3 × 3 × 3 × 3 × 7 × 7 × 7 × 7 × 251 × 251 × 251)See below for interesting mathematical facts about the number 806191593614475264 from the Numbermatics database.
Names of 806191593614475264
- Cardinal: 806191593614475264 can be written as Eight hundred six quadrillion, one hundred ninety-one trillion, five hundred ninety-three billion, six hundred fourteen million, four hundred seventy-five thousand, two hundred sixty-four.
Scientific notation
- Scientific notation: 8.06191593614475264 × 1017
Factors of 806191593614475264
Divisors of 806191593614475264
- Number of divisors d(n): 1900
-
Complete list of divisors:
1 2 3 4 6 7 8 9 12 14 16 18 21 24 27 28 32 36 42 48 49 54 56 63 64 72 81 84 96 98 108 112 126 128 144 147 162 168 189 192 196 216 224 251 252 256 288 294 324 336 343 378 384 392 432 441 448 502 504 512 567 576 588 648 672 686 753 756 768 784 864 882 896 1004 1008 1024 1029 1134 1152 1176 1296 1323 1344 1372 1506 1512 1536 1568 1728 1757 1764 1792 2008 2016 2048 2058 2259 2268 2304 2352 2401 2592 2646 2688 2744 3012 3024 3072 3087 3136 3456 3514 3528 3584 3969 4016 4032 4096 4116 4518 4536 4608 4704 4802 5184 5271 5292 5376 5488 6024 6048 6144 6174 6272 6777 6912 7028 7056 7168 7203 7938 8032 8064 8192 8232 9036 9072 9216 9261 9408 9604 10368 10542 10584 10752 10976 12048 12096 12288 12299 12348 12544 13554 13824 14056 14112 14336 14406 15813 15876 16064 16128 16384 16464 18072 18144 18432 18522 18816 19208 20331 20736 21084 21168 21504 21609 21952 24096 24192 24576 24598 24696 25088 27108 27648 27783 28112 28224 28672 28812 31626 31752 32128 32256 32768 32928 36144 36288 36864 36897 37044 37632 38416 40662 41472 42168 42336 43008 43218 43904 47439 48192 48384 49152 49196 49392 50176 54216 55296 55566 56224 56448 57344 57624 63001 63252 63504 64256 64512 64827 65536 65856 72288 72576 73728 73794 74088 75264 76832 81324 82944 84336 84672 86016 86093 86436 87808 94878 96384 96768 98304 98392 98784 100352 108432 110592 110691 111132 112448 112896 114688 115248 126002 126504 127008 128512 129024 129654 131072 131712 142317 144576 145152 147456 147588 148176 150528 153664 162648 165888 168672 169344 172032 172186 172872 175616 189003 189756 192768 193536 194481 196608 196784 197568 200704 216864 221184 221382 222264 224896 225792 229376 230496 252004 253008 254016 257024 258048 258279 259308 262144 263424 284634 289152 290304 294912 295176 296352 301056 307328 325296 331776 332073 337344 338688 344064 344372 345744 351232 378006 379512 385536 387072 388962 393216 393568 395136 401408 433728 441007 442368 442764 444528 449792 451584 458752 460992 504008 506016 508032 514048 516096 516558 518616 526848 567009 569268 578304 580608 589824 590352 592704 602112 602651 614656 650592 663552 664146 674688 677376 688128 688744 691488 702464 756012 759024 771072 774144 774837 777924 786432 787136 790272 802816 867456 882014 884736 885528 889056 899584 903168 917504 921984 996219 1008016 1012032 1016064 1028096 1032192 1033116 1037232 1053696 1134018 1138536 1156608 1161216 1179648 1180704 1185408 1204224 1205302 1229312 1301184 1323021 1327104 1328292 1349376 1354752 1376256 1377488 1382976 1404928 1512024 1518048 1542144 1548288 1549674 1555848 1574272 1580544 1605632 1701027 1734912 1764028 1769472 1771056 1778112 1799168 1806336 1807953 1835008 1843968 1992438 2016032 2024064 2032128 2056192 2064384 2066232 2074464 2107392 2268036 2277072 2313216 2322432 2324511 2359296 2361408 2370816 2408448 2410604 2458624 2602368 2646042 2654208 2656584 2698752 2709504 2752512 2754976 2765952 2809856 3024048 3036096 3084288 3087049 3096576 3099348 3111696 3148544 3161088 3211264 3402054 3469824 3528056 3538944 3542112 3556224 3598336 3612672 3615906 3687936 3969063 3984876 4032064 4048128 4064256 4112384 4128768 4132464 4148928 4214784 4536072 4554144 4626432 4644864 4649022 4722816 4741632 4816896 4821208 4917248 5103081 5204736 5292084 5308416 5313168 5397504 5419008 5423859 5505024 5509952 5531904 5619712 6048096 6072192 6168576 6174098 6193152 6198696 6223392 6297088 6322176 6422528 6804108 6939648 6973533 7056112 7077888 7084224 7112448 7196672 7225344 7231812 7375872 7938126 7969752 8064128 8096256 8128512 8224768 8257536 8264928 8297856 8429568 9072144 9108288 9252864 9261147 9289728 9298044 9445632 9483264 9633792 9642416 9834496 10206162 10409472 10584168 10616832 10626336 10795008 10838016 10847718 11019904 11063808 11239424 11907189 12096192 12144384 12337152 12348196 12386304 12397392 12446784 12594176 12644352 12845056 13608216 13879296 13947066 14112224 14168448 14224896 14393344 14450688 14463624 14751744 15813251 15876252 15939504 16128256 16192512 16257024 16271577 16449536 16515072 16529856 16595712 16859136 18144288 18216576 18505728 18522294 18579456 18596088 18891264 18966528 19267584 19284832 19668992 20412324 20818944 21168336 21233664 21252672 21590016 21609343 21676032 21695436 22039808 22127616 22478848 23814378 24192384 24288768 24674304 24696392 24772608 24794784 24893568 25188352 25288704 27216432 27758592 27783441 27894132 28224448 28336896 28449792 28786688 28901376 28927248 29503488 31626502 31752504 31879008 32256512 32385024 32514048 32543154 32899072 33059712 33191424 33718272 35721567 36288576 36433152 37011456 37044588 37158912 37192176 37782528 37933056 38535168 38569664 39337984 40824648 41637888 42336672 42505344 43180032 43218686 43352064 43390872 44079616 44255232 44957696 47439753 47628756 48384768 48577536 48814731 49348608 49392784 49545216 49589568 49787136 50376704 50577408 54432864 55517184 55566882 55788264 56448896 56673792 56899584 57573376 57802752 57854496 59006976 63253004 63505008 63758016 64513024 64770048 64828029 65028096 65086308 65798144 66119424 66382848 67436544 71443134 72577152 72866304 74022912 74089176 74317824 74384352 75565056 75866112 77139328 78675968 81649296 83275776 83350323 84673344 85010688 86360064 86437372 86704128 86781744 88159232 88510464 89915392 94879506 95257512 96769536 97155072 97629462 98697216 98785568 99179136 99574272 100753408 101154816 108865728 110692757 111034368 111133764 111576528 112897792 113347584 113799168 115146752 115605504 115708992 118013952 126506008 127010016 127516032 129026048 129540096 129656058 130056192 130172616 132238848 132765696 134873088 142319259 142886268 145154304 145732608 148045824 148178352 148635648 148768704 151130112 151265401 151732224 154278656 157351936 163298592 166551552 166700646 169346688 170021376 172720128 172874744 173408256 173563488 176318464 177020928 189759012 190515024 193539072 194310144 194484087 195258924 197394432 197571136 198358272 199148544 201506816 202309632 217731456 221385514 222068736 222267528 223153056 225795584 226695168 227598336 230293504 231417984 236027904 250050969 253012016 254020032 255032064 258052096 259080192 259312116 260112384 260345232 264477696 265531392 269746176 284638518 285772536 290308608 291465216 296091648 296356704 297537408 302260224 302530802 303464448 308557312 314703872 326597184 332078271 333103104 333401292 338693376 340042752 345440256 345749488 346816512 347126976 352636928 354041856 379518024 381030048 387078144 388620288 388968174 390517848 395142272 396716544 398297088 403013632 404619264 426957777 435462912 442771028 444137472 444535056 446306112 451591168 453390336 453796203 455196672 460587008 462835968 472055808 500101938 506024032 508040064 510064128 516104192 518160384 518624232 520224768 520690464 528955392 531062784 569277036 571545072 580617216 582930432 583452261 592183296 592713408 595074816 604520448 605061604 606928896 617114624 629407744 653194368 664156542 666206208 666802584 677386752 680085504 690880512 691498976 694253952 705273856 708083712 759036048 762060096 774156288 774849299 777240576 777936348 781035696 790284544 793433088 796594176 806027264 809238528 853915554 870925824 885542056 888274944 889070112 892612224 903182336 906780672 907592406 910393344 925671936 944111616 996234813 1000203876 1012048064 1016080128 1020128256 1032208384 1036320768 1037248464 1040449536 1041380928 1057910784 1062125568 1138554072 1143090144 1161234432 1165860864 1166904522 1185426816 1190149632 1209040896 1210123208 1213857792 1234229248 1280873331 1306388736 1328313084 1332412416 1333605168 1354773504 1360171008 1361388609 1381761024 1382997952 1388507904 1410547712 1416167424 1518072096 1524120192 1548312576 1549698598 1554481152 1555872696 1562071392 1580569088 1586866176 1593188352 1612054528 1707831108 1741851648 1750356783 1771084112 1776549888 1778140224 1785224448 1806364672 1813561344 1815184812 1820786688 1851343872 1888223232 1992469626 2000407752 2024096128 2032160256 2040256512 2064416768 2072641536 2074496928 2082761856 2115821568 2124251136 2277108144 2286180288 2322468864 2324547897 2331721728 2333809044 2370853632 2380299264 2418081792 2420246416 2427715584 2468458496 2561746662 2612777472 2656626168 2664824832 2667210336 2709547008 2720342016 2722777218 2765995904 2777015808 2821095424 2832334848 2988704439 3036144192 3048240384 3096625152 3099397196 3108962304 3111745392 3124142784 3161138176 3173732352 3186376704 3224109056 3415662216 3483703296 3500713566 3542168224 3556280448 3570448896 3612729344 3627122688 3630369624 3641573376 3702687744 3984939252 4000815504 4048192256 4064320512 4080513024 4084165827 4128833536 4145283072 4148993856 4165523712 4231643136 4248502272 4554216288 4572360576 4644937728 4649095794 4663443456 4667618088 4741707264 4760598528 4836163584 4840492832 4936916992 5123493324 5225554944 5313252336 5329649664 5334420672 5419094016 5423945093 5440684032 5445554436 5531991808 5554031616 5642190848 5664669696 5977408878 6072288384 6096480768 6193250304 6198794392 6217924608 6223490784 6248285568 6322276352 6347464704 6372753408 6831324432 6967406592 6973643691 7001427132 7084336448 7112560896 7140897792 7225458688 7254245376 7260739248 7283146752 7405375488 7969878504 8001631008 8096384512 8128641024 8161026048 8168331654 8257667072 8297987712 8331047424 8463286272 8497004544 8966113317 9108432576 9144721152 9289875456 9298191588 9326886912 9335236176 9483414528 9521197056 9672327168 9680985664 9873833984 10246986648 10451109888 10626504672 10668841344 10838188032 10847890186 10881368064 10891108872 11063983616 11108063232 11284381696 11954817756 12144576768 12192961536 12252497481 12386500608 12397588784 12435849216 12446981568 12496571136 12644552704 12694929408 12745506816 13662648864 13934813184 13947287382 14002854264 14168672896 14225121792 14281795584 14450917376 14508490752 14521478496 14810750976 15939757008 16003262016 16192769024 16257282048 16271835279 16322052096 16336663308 16515334144 16595975424 16662094848 16926572544 16994009088 17932226634 18216865152 18289442304 18579750912 18596383176 18653773824 18670472352 18966829056 19042394112 19361971328 19747667968 20493973296 20902219776 20920931073 21253009344 21337682688 21676376064 21695780372 21762736128 21782217744 22127967232 22216126464 22568763392 23909635512 24289153536 24385923072 24504994962 24773001216 24795177568 24893963136 24993142272 25289105408 25389858816 25491013632 27325297728 27869626368 27894574764 28005708528 28337345792 28450243584 28563591168 28901834752 29016981504 29042956992 29621501952 31879514016 32006524032 32385538048 32514564096 32543670558 32644104192 32673326616 33191950848 33324189696 33853145088 35864453268 36433730304 36578884608 37159501824 37192766352 37307547648 37340944704 37933658112 37967615651 38084788224 38723942656 39495335936 40987946592 41804439552 41841862146 42506018688 42675365376 43352752128 43391560744 43525472256 43564435488 44255934464 44432252928 47819271024 48578307072 48771846144 48815505837 49009989924 49546002432 49590355136 49787926272 49986284544 50578210816 50779717632 50982027264 54650595456 55739252736 55789149528 56011417056 56674691584 56900487168 57127182336 57803669504 58085913984 59243003904 62762793219 63759028032 64013048064 64771076096 65029128192 65087341116 65288208384 65346653232 66383901696 66648379392 67706290176 71728906536 72867460608 73157769216 74319003648 74385532704 74681889408 75867316224 75935231302 76169576448 77447885312 78990671872 81975893184 83608879104 83683724292 85012037376 85350730752 86705504256 86783121488 87050944512 87128870976 88511868928 88864505856 95638542048 97156614144 97543692288 97631011674 98019979848 99180710272 99575852544 99972569088 101156421632 101559435264 109301190912 111478505472 111578299056 112022834112 113349383168 113800974336 113902846953 114254364672 115607339008 116171827968 118486007808 125525586438 127518056064 128026096128 129542152192 130058256384 130174682232 130576416768 130693306464 132767803392 133296758784 143457813072 145734921216 146315538432 146446517511 148638007296 148771065408 149363778816 151734632448 151870462604 152339152896 154895770624 157981343744 163951786368 167217758208 167367448584 170024074752 170701461504 173411008512 173566242976 174257741952 177023737856 177729011712 191277084096 194313228288 195087384576 195262023348 196039959696 198361420544 199151705088 199945138176 202312843264 203118870528 218602381824 222957010944 223156598112 224045668224 226698766336 227601948672 227805693906 228508729344 232343655936 236972015616 251051172876 255036112128 256052192256 259084304384 260116512768 260349364464 261152833536 261386612928 265535606784 266593517568 286915626144 291469842432 292631076864 292893035022 297542130816 298727557632 303469264896 303740925208 304678305792 309791541248 327903572736 334435516416 334734897168 340048149504 341402923008 341708540859 346822017024 347132485952 348515483904 354047475712 355458023424 382554168192 388626456576 390174769152 390524046696 392079919392 396722841088 398303410176 399890276352 404625686528 437204763648 439339552533 445914021888 446313196224 448091336448 453397532672 455203897344 455611387812 457017458688 464687311872 473944031232 502102345752 510072224256 512104384512 518168608768 520233025536 520698728928 522773225856 531071213568 533187035136 573831252288 582939684864 585262153728 585786070044 595084261632 597455115264 606938529792 607481850416 609356611584 619583082496 655807145472 668871032832 669469794336 680096299008 682805846016 683417081718 694264971904 697030967808 708094951424 710916046848 765108336384 777252913152 780349538304 781048093392 784159838784 793445682176 796606820352 799780552704 809251373056 874409527296 878679105066 892626392448 896182672896 906795065344 910407794688 911222775624 914034917376 929374623744 1004204691504 1020144448512 1024208769024 1025125622577 1036337217536 1040466051072 1041397457856 1045546451712 1062142427136 1066374070272 1147662504576 1165879369728 1170524307456 1171572140088 1190168523264 1194910230528 1213877059584 1214963700832 1239166164992 1311614290944 1337742065664 1338939588672 1360192598016 1365611692032 1366834163436 1388529943808 1394061935616 1416189902848 1421832093696 1530216672768 1554505826304 1560699076608 1562096186784 1568319677568 1586891364352 1593213640704 1599561105408 1748819054592 1757358210132 1785252784896 1792365345792 1813590130688 1820815589376 1822445551248 1828069834752 1858749247488 2008409383008 2040288897024 2048417538048 2050251245154 2072674435072 2082794915712 2091092903424 2124284854272 2132748140544 2295325009152 2331758739456 2341048614912 2343144280176 2380337046528 2389820461056 2427754119168 2429927401664 2478332329984 2623228581888 2677879177344 2720385196032 2731223384064 2733668326872 2777059887616 2788123871232 2832379805696 3060433345536 3075376867731 3109011652608 3121398153216 3124192373568 3136639355136 3173782728704 3186427281408 3199122210816 3497638109184 3514716420264 3570505569792 3584730691584 3627180261376 3641631178752 3644891102496 3717498494976 4016818766016 4080577794048 4096835076096 4100502490308 4145348870144 4165589831424 4182185806848 4248569708544 4265496281088 4590650018304 4663517478912 4682097229824 4686288560352 4760674093056 4779640922112 4859854803328 4956664659968 5246457163776 5355758354688 5440770392064 5462446768128 5467336653744 5554119775232 5576247742464 5664759611392 6120866691072 6150753735462 6218023305216 6248384747136 6273278710272 6347565457408 6372854562816 6398244421632 6995276218368 7029432840528 7141011139584 7169461383168 7254360522752 7283262357504 7289782204992 7434996989952 8033637532032 8161155588096 8193670152192 8201004980616 8331179662848 8364371613696 8497139417088 9181300036608 9327034957824 9364194459648 9372577120704 9521348186112 9559281844224 9719709606656 9913329319936 10492914327552 10711516709376 10881540784128 10924893536256 10934673307488 11108239550464 11152495484928 12241733382144 12301507470924 12436046610432 12496769494272 12546557420544 12695130914816 12745709125632 12796488843264 13990552436736 14058865681056 14282022279168 14338922766336 14508721045504 14579564409984 14869993979904 16067275064064 16322311176192 16387340304384 16402009961232 16662359325696 16728743227392 16994278834176 18362600073216 18654069915648 18745154241408 19042696372224 19118563688448 19439419213312 19826658639872 20985828655104 21423033418752 21763081568256 21849787072512 21869346614976 22216479100928 22304990969856 24483466764288 24603014941848 24993538988544 25093114841088 25390261829632 25491418251264 27981104873472 28117731362112 28564044558336 28677845532672 29017442091008 29159128819968 29739987959808 32134550128128 32644622352384 32774680608768 32804019922464 33324718651392 33457486454784 36725200146432 37308139831296 37490308482816 38085392744448 38237127376896 38878838426624 39653317279744 41971657310208 42846066837504 43526163136512 43738693229952 44432958201856 44609981939712 48966933528576 49206029883696 49987077977088 50186229682176 50780523659264 50982836502528 55962209746944 56235462724224 57128089116672 57355691065344 58318257639936 59479975919616 64269100256256 65289244704768 65549361217536 65608039844928 66649437302784 66914972909568 73450400292864 74980616965632 76170785488896 76474254753792 77757676853248 83943314620416 85692133675008 87052326273024 87477386459904 88865916403712 89219963879424 97933867057152 98412059767392 99974155954176 100372459364352 101561047318528 111924419493888 112470925448448 114256178233344 114711382130688 116636515279872 118959951839232 128538200512512 130578489409536 131216079689856 133298874605568 133829945819136 146900800585728 149961233931264 152341570977792 152948509507584 155515353706496 167886629240832 171384267350016 174954772919808 177731832807424 178439927758848 195867734114304 196824119534784 199948311908352 200744918728704 203122094637056 224941850896896 228512356466688 229422764261376 233273030559744 257076401025024 261156978819072 262432159379712 266597749211136 267659891638272 293801601171456 299922467862528 304683141955584 311030707412992 335773258481664 342768534700032 349909545839616 355463665614848 356879855517696 391735468228608 393648239069568 399896623816704 401489837457408 449883701793792 457024712933376 458845528522752 466546061119488 514152802050048 524864318759424 533195498422272 535319783276544 587603202342912 599844935725056 609366283911168 622061414825984 685537069400064 699819091679232 710927331229696 783470936457216 787296478139136 799793247633408 802979674914816 899767403587584 914049425866752 933092122238976 1028305604100096 1049728637518848 1066390996844544 1070639566553088 1175206404685824 1199689871450112 1244122829651968 1371074138800128 1399638183358464 1421854662459392 1574592956278272 1599586495266816 1605959349829632 1799534807175168 1828098851733504 1866184244477952 2056611208200192 2099457275037696 2132781993689088 2350412809371648 2399379742900224 2488245659303936 2742148277600256 2799276366716928 3149185912556544 3199172990533632 3211918699659264 3599069614350336 3732368488955904 4113222416400384 4198914550075392 4265563987378176 4798759485800448 4976491318607872 5484296555200512 5598552733433856 6298371825113088 6398345981067264 7198139228700672 7464736977911808 8226444832800768 8397829100150784 9597518971600896 9952982637215744 11197105466867712 12596743650226176 12796691962134528 14396278457401344 14929473955823616 16452889665601536 16795658200301568 19195037943201792 22394210933735424 25193487300452352 28792556914802688 29858947911647232 33591316400603136 38390075886403584 44788421867470848 50386974600904704 57585113829605376 67182632801206272 89576843734941696 100773949201809408 115170227659210752 134365265602412544 201547898403618816 268730531204825088 403095796807237632 806191593614475264
- Sum of all divisors σ(n): 2821125753520112808
- Sum of proper divisors (its aliquot sum) s(n): 2014934159905637544
- 806191593614475264 is an abundant number, because the sum of its proper divisors (2014934159905637544) is greater than itself. Its abundance is 1208742566291162280
Bases of 806191593614475264
- Binary: 1011001100000010101011111011101001100100110000000000000000002
- Hexadecimal: 0xB302AFBA64C0000
- Base-36: 64I32H8JY800
Squares and roots of 806191593614475264
- 806191593614475264 squared (8061915936144752642) is 649944885614647233264090954067869696
- 806191593614475264 cubed (8061915936144752643) is 523980103095250292291730236883687571055531833367199744
-
The
square root of 806191593614475264 is 897881725.8494992135 -
The
cube root of 806191593614475264 is 930706.5173571127
Scales and comparisons
How big is 806191593614475264?- 806,191,593,614,475,264 seconds is equal to 25,634,398,962 years, 31 weeks, 4 days, 18 hours, 14 minutes, 24 seconds.
-
To count from 1 to 806,191,593,614,475,264 would take you about seventy-six billion, nine hundred three million, one hundred ninety-six thousand, eight hundred eighty-seven years!
This is a very rough estimate, based on a speaking rate of half a second every third order of magnitude. If you speak quickly, you could probably say any randomly-chosen number between one and a thousand in around half a second. Very big numbers obviously take longer to say, so we add half a second for every extra x1000. (We do not count involuntary pauses, bathroom breaks or the necessity of sleep in our calculation!)
- A cube with a volume of 806191593614475264 cubic inches would be around 77558.9 feet tall.
Recreational maths with 806191593614475264
- 806191593614475264 backwards is 462574416395191608
- 806191593614475264 is a
Harshad number . - The number of decimal digits it has is: 18
- The sum of 806191593614475264's digits is 81
- More coming soon!
Link to this page
HTML: To link to this page, just copy and paste the link below into your blog, web page or email.
BBCODE: To link to this page in a forum post or comment box, just copy and paste the link code below:
Cite this page
MLA style:
"Number 806191593614475264 - Facts about the integer". Numbermatics.com. 2024. Web. 4 June 2024.
APA style:
Numbermatics. (2024). Number 806191593614475264 - Facts about the integer. Retrieved 4 June 2024, from https://numbermatics.com/n/806191593614475264/
Chicago style:
Numbermatics. 2024. "Number 806191593614475264 - Facts about the integer". https://numbermatics.com/n/806191593614475264/
The information we have on file for 806191593614475264 includes mathematical data and numerical statistics calculated using standard algorithms and methods. We are adding more all the time. If there are any features you would like to see, please contact us. Information provided for educational use, intellectual curiosity and fun!
Keywords: Divisors of 806191593614475264, math, Factors of 806191593614475264, curriculum, school, college, exams, university, Prime factorization of 806191593614475264, STEM, science, technology, engineering, physics, economics, calculator, eight hundred six quadrillion, one hundred ninety-one trillion, five hundred ninety-three billion, six hundred fourteen million, four hundred seventy-five thousand, two hundred sixty-four.