455

Number
$455$ (four hundred and fifty-five) is:


 * $5 \times 7 \times 13$


 * The $13$th tetrahedral number, after $1$, $4$, $10$, $20$, $35$, $56$, $84$, $120$, $165$, $220$, $286$, $364$:
 * $455 = \displaystyle \sum_{k \mathop = 1}^{13} \frac {k \left({k + 1}\right)} 2 = \dfrac {13 \left({13 + 1}\right) \left({13 + 2}\right)} 6$