1653

Number
$1653$ (one thousand, six hundred and fifty-three) is:
 * $3 \times 19 \times 29$


 * The $29$th hexagonal number after $1$, $6$, $15$, $28$, $45$, $66$, $91$, $\ldots$, $703$, $780$, $861$, $946$, $1035$, $1225$, $1326$, $1431$, $1540$:
 * $1653 = \displaystyle \sum_{k \mathop = 1}^{29} \left({4 k - 3}\right) = 29 \left({2 \times 29 - 1}\right)$