880

Number
$880$ (eight hundred and eighty) is:


 * $2^4 \times 5 \times 11$


 * The number of different magic squares of order $4$, up to rotation and reflection


 * The $7$th and last of the $3$-digit integers $m$ which need the largest number of reverse-and-add process iterations ($23$) before reaching a palindromic number:
 * $880$, $968$, $1837$, $\ldots$, $8 \, 713 \, 200 \, 023 \, 178$


 * The $10$th heptagonal pyramidal number after $1$, $8$, $26$, $60$, $115$, $196$, $308$, $456$, $645$:
 * $880 = 1 + 7 + 18 + 34 + 55 + 81 + 112 + 148 + 189 + 235 = \dfrac {10 \paren {10 + 1} \paren {5 \times 10 + 2} } 6$

Also see

 * Number of Magic Squares of Order 4