1140

Number
$1140$ (one thousand, one hundred and forty) is:
 * $2^2 \times 3 \times 5 \times 19$


 * The $18$th tetrahedral number, after $1$, $4$, $10$, $20$, $35$, $56$, $84$, $120$, $165$, $220$, $286$, $364$, $455$, $560$, $680$, $816$, $969$:
 * $1140 = \displaystyle \sum_{k \mathop = 1}^{18} \frac {k \left({k + 1}\right)} 2 = \dfrac {18 \left({18 + 1}\right) \left({18 + 2}\right)} 6$