2791

Number
$2791$ (two thousand, seven hundred and ninety-one) is:


 * The $406$th prime number


 * The $31$st centered hexagonal number after $1$, $7$, $19$, $37$, $61$, $91$, $127$, $\ldots$, $1387$, $1519$, $1657$, $1801$, $1951$, $2107$, $2269$, $2437$, $2611$:
 * $2791 = \displaystyle 1 + \sum_{k \mathop = 1}^{31 - 1} 6 k = 31^3 - 30^3$