6816

Number
$6816$ (six thousand, eight hundred and sixteen) is:
 * $2^5 \times 3 \times 71$


 * The $48$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $\ldots$, $5985$, $6256$, $6533$:
 * $6816 = \displaystyle \sum_{k \mathop = 1}^{48} \left({6 k - 5}\right) = 48 \left({3 \times 48 - 2}\right)$