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

45 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 45:

32 × 5

(3 × 3 × 5)

See below for interesting mathematical facts about the number 45 from the Numbermatics database.

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Names Factors Divisors Scales Roots Fun

Names of 45

  • Cardinal: 45 can be written as Forty-five.

Scientific notation

  • Scientific notation: 4.5 × 101

Factors of 45

  • Number of distinct prime factors ω(n): 2
  • Total number of prime factors Ω(n): 3
  • Sum of prime factors: 8

Divisors of 45

  • Number of divisors d(n): 6
  • Complete list of divisors:
    1 3 5 9 15 45
  • Sum of all divisors σ(n): 78
  • Sum of proper divisors (its aliquot sum) s(n): 33
  • 45 is a deficient number, because the sum of its proper divisors (33) is less than itself. Its deficiency is 12

Bases of 45

  • Binary: 101101 2
  • Hexadecimal: 0x2d

Squares and roots of 45

  • 45 squared (452) is 2025
  • 45 cubed (453) is 91125
  • The square root of 45 is 6.7082039325
  • The cube root of 45 is 3.5568933047

Scales and comparisons

How big is 45?
  • To count from 1 to 45 would take you about twenty-two seconds.

    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.

    Note: we do not count involuntary pauses, bathroom breaks or the necessity of sleep in our calculation!

  • A cube with a volume of 45 cubic inches would be around 0.3 feet tall.

Recreational maths with 45

  • 45 backwards is 54
  • 45 is a Harshad number.
  • The number of decimal digits it has is: 2
  • The sum of 45's digits is 9
  • More coming soon!

The information we have on file for 45 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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