21,661 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 21661 look like?

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

21661 is a prime number. Like all primes (except two), it is an odd number.

Prime factorization of 21661:


See below for interesting mathematical facts about the number 21661 from the Numbermatics database.

Names of 21661

  • Cardinal: 21661 can be written as Twenty-one thousand, six hundred sixty-one.

Scientific notation

  • Scientific notation: 2.1661 × 104

Factors of 21661

  • Number of distinct prime factors ω(n): 1
  • Total number of prime factors Ω(n): 1
  • Sum of prime factors: 21661

Divisors of 21661

  • Number of divisors d(n): 2
  • Complete list of divisors:
  • Sum of all divisors σ(n): 21662
  • Sum of proper divisors (its aliquot sum) s(n): 1
  • 21661 is a deficient number, because the sum of its proper divisors (1) is less than itself. Its deficiency is 21660

Bases of 21661

  • Binary: 1010100100111012
  • Hexadecimal: 0x549D
  • Base-36: GPP

Squares and roots of 21661

  • 21661 squared (216612) is 469198921
  • 21661 cubed (216613) is 10163317827781
  • The square root of 21661 is 147.1767644705
  • The cube root of 21661 is 27.8757247427

Scales and comparisons

How big is 21661?
  • 21,661 seconds is equal to 6 hours, 1 minute, 1 second.
  • To count from 1 to 21,661 would take you about six 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 21661 cubic inches would be around 2.3 feet tall.

Recreational maths with 21661

  • 21661 backwards is 16612
  • The number of decimal digits it has is: 5
  • The sum of 21661's digits is 16
  • More coming soon!

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"Number 21661 - Facts about the integer". Numbermatics.com. 2021. Web. 4 December 2021.

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Numbermatics. (2021). Number 21661 - Facts about the integer. Retrieved 4 December 2021, from https://numbermatics.com/n/21661/

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Numbermatics. 2021. "Number 21661 - Facts about the integer". https://numbermatics.com/n/21661/

The information we have on file for 21661 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 21661, math, Factors of 21661, curriculum, school, college, exams, university, Prime factorization of 21661, STEM, science, technology, engineering, physics, economics, calculator, twenty-one thousand, six hundred sixty-one.

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