378

Number
$378$ (three hundred and seventy-eight) is:


 * $2 \times 3^3 \times 7$


 * The $27$th triangular number after $1, 3, 6, 10, 15, \ldots, 171, 190, 210, 231, 253, 276, 300, 325, 351$:
 * $378 = \displaystyle \sum_{k \mathop = 1}^{27} k = \dfrac {27 \times \left({27 + 1}\right)} 2$


 * The $14$th hexagonal number after $1, 6, 15, 28, 45, 66, 91, 120, 153, 190, 231, 276, 325$:
 * $378 = \displaystyle \sum_{k \mathop = 1}^{14} \left({4 k - 3}\right) = 14 \left({2 \times 14 - 1}\right)$