936

Number
$936$ (nine hundred and thirty-six) is:


 * $2^3 \times 3^2 \times 13$


 * The $18$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $96$, $133$, $176$, $225$, $280$, $341$, $408$, $481$, $560$, $645$, $736$, $833$:
 * $936 = \displaystyle \sum_{k \mathop = 1}^{18} \left({6 k - 5}\right) = 18 \left({3 \times 18 - 2}\right)$


 * The $12$th pentagonal pyramidal number after $1$, $6$, $12$, $40$, $75$, $126$, $196$, $288$, $405$, $550$, $726$:
 * $936 = \displaystyle \sum_{k \mathop = 1}^{12} \dfrac {k \left({3 k - 1}\right)} 2 = \dfrac {12^2 \left({12 + 1}\right)} 2$