24

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24 < 23 | 25 >
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24 (twenty-four) is a positive integer following 23 and preceding 25. Its ordinal form is written "24th" or "twenty-fourth".

Properties

• 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 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) = a^a. Then for every a ∈ ℕ, there is a b ∈ ℕ, such that f^b+1(a) ≡ f^b(a) (mod n).
• HaydenTheGoogologist2009 coined Yummy! for this number, and it's the 3rd number in Meet yourself in 105 degrees Celsius.
• DeepLineMadom calls the number unoo-tedecol.

Googological functions returning 24

• Factorial: 4! = 24
• Torian: \(T(3)=24\)
• Bouncing factorial: \(3\Lambda = 24\)

See also

• Septillion, 10²⁴ using the short scale
• Factorial