24 (twenty-four) is a positive integer following 23 and preceding 25.

Properties

  • 24 is an even composite number[1] and the fourth factorial number.
  • There are 24 hours in a day.
  • The 24th of December is known around the world as Christmas eve.
  • 24 is the largest number divisible by all integers less than its square root.
  • It is the smallest positive integer whose square contains the digit 7.
  • It is the 3rd smallest number that is known to be friendly. Its smallest friend is 91963648.
  • It is the smallest non-unitary perfect number.

In googology

  • In Greek-based number-naming systems, 24 is associated with prefix "tetraicosa-", and with prefix "quattuorviginti-" in Latin systems. In the Misalian seximal system, this number is called "foursy", because it's six times four.
  • Furthermore, it is the largest number n with the following property: Let f: ℕ → ℕ, f(a) = aa. Then for every a ∈ ℕ, there is a b ∈ ℕ, such that fb+1(a) ≡ fb(a) (mod n).

Googological functions returning 24

24.jpeg

See also

Sources

  1. OEIS, sequence A002808 (accessed 2020-11-13)
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