44

Number
$44$ (forty-four) is:


 * $2^2 \times 11$


 * The $5$th subfactorial after $0, 1, 2, 9$:
 * $44 = 5! \left({1 - \dfrac 1 {1!} + \dfrac 1 {2!} - \dfrac 1 {3!} + \dfrac 1 {4!} - \dfrac 1 {5!} }\right)$


 * The $10$th happy number after $1, 7, 10, 13, 19, 23, 28, 31, 32$:
 * $44 \to 4^2 + 4^2 = 16 + 16 = 32 \to 3^2 + 2^2 = 9 + 4 = 13 \to 1^2 + 3^2 = 9 + 1 = 10 \to 1^2 + 0^2 = 1$