20991

20,991 is an odd composite number composed of two prime numbers multiplied together.

What does the number 20991 look like?

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

20991 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 20991:

3 × 6997

See below for interesting mathematical facts about the number 20991 from the Numbermatics database.


Names of 20991

  • Cardinal: 20991 can be written as Twenty thousand, nine hundred ninety-one.

Scientific notation

  • Scientific notation: 2.0991 × 104

Factors of 20991

  • Number of distinct prime factors ω(n): 2
  • Total number of prime factors Ω(n): 2
  • Sum of prime factors: 7000

Divisors of 20991

  • Number of divisors d(n): 4
  • Complete list of divisors:
  • Sum of all divisors σ(n): 27992
  • Sum of proper divisors (its aliquot sum) s(n): 7001
  • 20991 is a deficient number, because the sum of its proper divisors (7001) is less than itself. Its deficiency is 13990

Bases of 20991

  • Binary: 1010001111111112
  • Hexadecimal: 0x51FF
  • Base-36: G73

Squares and roots of 20991

  • 20991 squared (209912) is 440622081
  • 20991 cubed (209913) is 9249098102271
  • The square root of 20991 is 144.8827111839
  • The cube root of 20991 is 27.5852998803

Scales and comparisons

How big is 20991?
  • 20,991 seconds is equal to 5 hours, 49 minutes, 51 seconds.
  • To count from 1 to 20,991 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 20991 cubic inches would be around 2.3 feet tall.

Recreational maths with 20991

  • 20991 backwards is 19902
  • The number of decimal digits it has is: 5
  • The sum of 20991's digits is 21
  • More coming soon!

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"Number 20991 - Facts about the integer". Numbermatics.com. 2024. Web. 28 March 2024.

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Numbermatics. (2024). Number 20991 - Facts about the integer. Retrieved 28 March 2024, from https://numbermatics.com/n/20991/

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Numbermatics. 2024. "Number 20991 - Facts about the integer". https://numbermatics.com/n/20991/

The information we have on file for 20991 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 20991, math, Factors of 20991, curriculum, school, college, exams, university, Prime factorization of 20991, STEM, science, technology, engineering, physics, economics, calculator, twenty thousand, nine hundred ninety-one.

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