18991

18,991 is an odd composite number composed of two prime numbers multiplied together.

What does the number 18991 look like?

This visualization shows the relationship between its 2 prime factors (large circles) and 4 divisors.

18991 is an odd composite number. It is composed of two distinct prime numbers multiplied together. It has a total of four divisors.

Prime factorization of 18991:

7 × 2713

See below for interesting mathematical facts about the number 18991 from the Numbermatics database.


Names of 18991

  • Cardinal: 18991 can be written as Eighteen thousand, nine hundred ninety-one.

Scientific notation

  • Scientific notation: 1.8991 × 104

Factors of 18991

  • Number of distinct prime factors ω(n): 2
  • Total number of prime factors Ω(n): 2
  • Sum of prime factors: 2720

Divisors of 18991

  • Number of divisors d(n): 4
  • Complete list of divisors:
  • Sum of all divisors σ(n): 21712
  • Sum of proper divisors (its aliquot sum) s(n): 2721
  • 18991 is a deficient number, because the sum of its proper divisors (2721) is less than itself. Its deficiency is 16270

Bases of 18991

  • Binary: 1001010001011112
  • Hexadecimal: 0x4A2F
  • Base-36: ENJ

Squares and roots of 18991

  • 18991 squared (189912) is 360658081
  • 18991 cubed (189913) is 6849257616271
  • The square root of 18991 is 137.8078372227
  • The cube root of 18991 is 26.6798025561

Scales and comparisons

How big is 18991?
  • 18,991 seconds is equal to 5 hours, 16 minutes, 31 seconds.
  • To count from 1 to 18,991 would take you about five 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 18991 cubic inches would be around 2.2 feet tall.

Recreational maths with 18991

  • 18991 backwards is 19981
  • The number of decimal digits it has is: 5
  • The sum of 18991's digits is 28
  • More coming soon!

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The information we have on file for 18991 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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