1653

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


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


 * The $57$th triangular number after $1$, $3$, $6$, $10$, $15$, $\ldots$, $990$, $1035$, $1081$, $1128$, $1176$, $1225$, $1275$, $1326$, $1378$, $1431$, $1485$, $1540$, $1596$:
 * $1653 = \displaystyle \sum_{k \mathop = 1}^{57} k = \dfrac {57 \times \paren {57 + 1} } 2$