4485

Number
$4485$ (four thousand, four hundred and eighty-five) is:


 * $3 \times 5 \times 13 \times 23$


 * The $39$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $\ldots$, $3008$, $3201$, $3400$, $3605$, $3816$, $4033$, $4256$:
 * $4485 = \displaystyle \sum_{k \mathop = 1}^{39} \left({6 k - 5}\right) = 39 \left({3 \times 39 - 2}\right)$