- 24 is an even composite number 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 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
- OEIS, sequence A002808 (accessed 2020-11-13)
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