261

261 is an odd composite number composed of two prime numbers multiplied together.

What does the number 261 look like?

This visualization shows the relationship between its 2 prime factors (large circles) and 6 divisors.

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

Prime factorization of 261:

32 × 29

(3 × 3 × 29)

See below for interesting mathematical facts about the number 261 from the Numbermatics database.


Names of 261

  • Cardinal: 261 can be written as Two hundred sixty-one.

Scientific notation

  • Scientific notation: 2.61 × 102

Factors of 261

  • Number of distinct prime factors ω(n): 2
  • Total number of prime factors Ω(n): 3
  • Sum of prime factors: 32

Divisors of 261

  • Number of divisors d(n): 6
  • Complete list of divisors:
    1 3 9 29 87 261
  • Sum of all divisors σ(n): 390
  • Sum of proper divisors (its aliquot sum) s(n): 129
  • 261 is a deficient number, because the sum of its proper divisors (129) is less than itself. Its deficiency is 132

Bases of 261

  • Binary: 1000001012
  • Hexadecimal: 0x105
  • Base-36: 79

Squares and roots of 261

  • 261 squared (2612) is 68121
  • 261 cubed (2613) is 17779581
  • The square root of 261 is 16.1554944211
  • The cube root of 261 is 6.3906765287

Scales and comparisons

How big is 261?
  • 261 seconds is equal to 4 minutes, 21 seconds.
  • To count from 1 to 261 would take you about two minutes.

    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 261 cubic inches would be around 0.5 feet tall.

Recreational maths with 261

  • 261 backwards is 162
  • 261 is a Harshad number.
  • The number of decimal digits it has is: 3
  • The sum of 261's digits is 9
  • More coming soon!

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The information we have on file for 261 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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