247

Number
$247$ (two hundred and forty-seven) is:


 * $13 \times 19$


 * The $13$th pentagonal number after $1, 5, 12, 22, 35, 51, 70, 92, 117, 145, 176, 210$:
 * $247 = 1 + 4 + 7 + 10 + 13 + 16 + 19 + 22 + 25 + 28 + 31 + 34 + 37 = \dfrac {13 \left({3 \times 13 - 1}\right)} 2$


 * The $25$th generalized pentagonal number after $1, 2, 5, 7, 12, 15, \ldots, 126, 145, 176, 187, 210, 222$:
 * $247 = \dfrac {13 \left({3 \times 13 - 1}\right)} 2$


 * The $48$th positive integer $n$ such that no factorial of an integer can end with $n$ zeroes.