342

Number
$342$ (three hundred and forty-two) is:


 * $2 \times 3^2 \times 19$


 * The $12$th heptagonal number after $1, 7, 18, 34, 55, 81, 112, 148, 189, 235, 286$:
 * $342 = 1 + 7 + 11 + 16 + 21 + 26 + 31 + 36 + 41 + 46 + 51 + 56 = \dfrac {12 \left({5 \times 12 - 3}\right)} 2$


 * The $29$th untouchable number after $2, 5, 52, 88, 96, 120, 124, \ldots, 262, 268, 276, 288, 290, 292, 304, 306, 322, 324, 326, 336$.