24

Number
$24$ (twenty-four) is:


 * $2^3 \times 3$


 * $4$ factorial:
 * $24 = 4! = 4 \times 3 \times 2 \times 1$


 * The $5$th semiperfect number after $6, 12, 18, 20$:
 * $24 = 1 + 3 + 8 + 12$


 * Divisible by both the sum and product of its digits:
 * $24 = 4 \times \left({2 + 4}\right) = 3 \times \left({2 \times 4}\right)$


 * The smallest composite number the product of whose proper divisors form a cube:
 * $1 \times 2 \times 3 \times 4 \times 6 \times 8 \times 12 = 24^3$


 * The area of the smallest scalene obtuse triangle with integer sides and area:
 * $24 = \sqrt{16 \left({16 - 4}\right) \left({16 - 13}\right) \left({16 - 15}\right)}$
 * where $16 = \dfrac{4 + 13 + 15} 2$


 * The smallest positive integer which can be partitioned into distinct Fibonacci numbers in $5$ different ways:
 * $24 = 21 + 3 = 21 + 2 + 1 = 13 + 8 + 3 = 13 + 8 + 2 + 1 = 13 + 5 + 3 + 2 + 1$


 * The $24$th pyramidal number is a square:
 * $1^2 + 2^2 + \cdots + 24^2 = 70^2$

Also see

 * Sum of Squares of Divisors of 24 and 26 are Equal
 * Smallest Scalene Obtuse Triangle with Integer Sides and Area
 * Smallest Positive Integer with 5 Fibonacci Partitions