2356

Number
$2356$ (two thousand, three hundred and fifty-six) is:
 * $2^2 \times 19 \times 31$


 * The $31$st heptagonal number after $1, 7, 18, 34, 55, 81, 112, \ldots, 1525, 1651, 1782, 1918, 2059, 2205$:
 * $2356 = \displaystyle \sum_{k \mathop = 1}^{31} \left({5 k - 4}\right) = \dfrac {31 \left({5 \times 31 - 3}\right)} 2$