816

Number
$816$ (eight hundred and sixteen) is:
 * $2^4 \times 3 \times 17$


 * The $16$th tetrahedral number, after $1$, $4$, $10$, $20$, $35$, $56$, $84$, $120$, $165$, $220$, $286$, $364$, $455$, $560$, $680$:
 * $816 = \displaystyle \sum_{k \mathop = 1}^{16} \frac {k \left({k + 1}\right)} 2 = \dfrac {16 \left({16 + 1}\right) \left({16 + 2}\right)} 6$