351

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


 * $3^3 \times 13$


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