15,991 is a prime number. Like all primes greater than two, it is odd and has no factors apart from itself and one.

What does the number 15991 look like?

As a prime, it is not composed of any other numbers and has no internal structure.

15991 is a prime number. Like all primes (except two), it is an odd number.

Prime factorization of 15991:


See below for interesting mathematical facts about the number 15991 from the Numbermatics database.

Names of 15991

  • Cardinal: 15991 can be written as Fifteen thousand, nine hundred ninety-one.

Scientific notation

  • Scientific notation: 1.5991 × 104

Factors of 15991

  • Number of distinct prime factors ω(n): 1
  • Total number of prime factors Ω(n): 1
  • Sum of prime factors: 15991

Divisors of 15991

  • Number of divisors d(n): 2
  • Complete list of divisors:
  • Sum of all divisors σ(n): 15992
  • Sum of proper divisors (its aliquot sum) s(n): 1
  • 15991 is a deficient number, because the sum of its proper divisors (1) is less than itself. Its deficiency is 15990

Bases of 15991

  • Binary: 111110011101112
  • Hexadecimal: 0x3E77
  • Base-36: CC7

Squares and roots of 15991

  • 15991 squared (159912) is 255712081
  • 15991 cubed (159913) is 4089091887271
  • The square root of 15991 is 126.4555257789
  • The cube root of 15991 is 25.1936954079

Scales and comparisons

How big is 15991?
  • 15,991 seconds is equal to 4 hours, 26 minutes, 31 seconds.
  • To count from 1 to 15,991 would take you about four hours.

    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 15991 cubic inches would be around 2.1 feet tall.

Recreational maths with 15991

  • 15991 backwards is 19951
  • The number of decimal digits it has is: 5
  • The sum of 15991's digits is 25
  • More coming soon!

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The information we have on file for 15991 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!

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