1240

Number
$1240$ (one thousand, two hundred and forty) is:


 * $2^3 \times 5 \times 31$


 * The $15$th square pyramidal number after $1$, $5$, $14$, $30$, $55$, $91$, $140$, $204$, $285$, $385$, $506$, $650$, $819$, $1015$:
 * $1240 = \displaystyle \sum_{k \mathop = 1}^{15} k^2 = \dfrac {15 \left({15 + 1}\right) \left({2 \times 15 + 1}\right)} 6$