385

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


 * $5 \times 7 \times 11$


 * The $42$nd sphenic number after $30$, $42$, $66$, $70$, $\ldots$, $290$, $310$, $318$, $322$, $345$, $354$, $357$, $366$, $370$, $374$:
 * $385 = 5 \times 7 \times 11$


 * 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:
 * $385$, $968$, $1837$, $\ldots$, $8713200023178$