351

Number
$351$ (three hundred and fifty-one) is:


 * $3^3 \times 13$


 * The $26$th triangular number after $1$, $3$, $6$, $10$, $15$, $\ldots$, $171$, $190$, $210$, $231$, $253$, $276$, $300$, $325$:
 * $351 = \displaystyle \sum_{k \mathop = 1}^{26} k = \dfrac {26 \times \left({26 + 1}\right)} 2$