The Natural Number 81

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Properties of the Number 81

  • Because 81 is not divisible by 2 ...
    • 81 is an odd number
    • 81 has parity 1
    • 81 is not an even number
  • Because 81 can be factored as 3 x 27 ...
    • 81 is a composite number
    • 81 is not a prime number

Alternative Representations of the Number 81

  • Base 2 (binary): 1010001
  • Base 8 (octal): 121
  • Base 16 (hexadecimal): 51
  • Roman numeral: LXXXI
  • Words: eighty-one

Divisors of the Number 81

  • 81 has 5 positive divisors: 1, 3, 9, 27, 81
    • The sum of the positive divisors is 121
  • 81 has 4 proper divisors: 1, 3, 9, 27
    • The sum of the proper divisors is 40
  • 81 is a deficient number since the sum of the proper divisors is less than 81
  • 81 is not a perfect number
  • 81 is not an abundant number

More Properties of the Number 81

  • 81 is a square number (i.e., square of the natural number 9)
  • 81 is not a cube number
  • 81 is not a palindromic number
  • 81 is not a Fibonacci number
  • 81 is not a Lucas number

12:06 am, Friday, March 24, 2017 (UTC; +0000)
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