56

Number
$56$ (fifty-six) is:


 * $2^3 \times 7$


 * The $6$th tetrahedral number, after $1, 4, 10, 20, 35$:
 * $56 = 1 + 3 + 6 + 10 + 15 + 21 = \dfrac {6 \left({6 + 1}\right) \left({6 + 2}\right)} 6$