7105

Number
$7105$ (seven thousand, one hundred and five) is:
 * $5 \times 7^2 \times 29$


 * The $49$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $\ldots$, $5985$, $6256$, $6533$, $6816$:
 * $7105 = \displaystyle \sum_{k \mathop = 1}^{49} \left({6 k - 5}\right) = 49 \left({3 \times 49 - 2}\right)$