385

Number
$385$ (three hundred and eighty-five) is:


 * $5 \times 7 \times 11$


 * The $10$th square pyramidal number after $1, 5, 14, 30, 55, 91, 140, 204, 285$:
 * $385 = \displaystyle \sum_{k \mathop = 1}^{10} k^2 = \dfrac {10 \left({10 + 1}\right) \left({2 \times 10 + 1}\right)} 6$


 * The $7$th Cullen number after $1, 3, 9, 25, 65, 161$:
 * $385 = 6 \times 2^6 + 1$


 * The $23$rd number whose $\sigma$ value is square:


 * The $3$rd of the $3$-digit integers $m$ which need the largest number of reverse-and-add process iterations ($23$) before reaching a palindromic number:
 * $385, 968, 1837, \ldots, 8713200023178$