9. When the positive integer $m$ satisfies what condition,
$$1^{3}+2^{3}+\cdots+(m-1)^{3}+m^{3} \equiv 0(\bmod m)$$

is always true (without calculating the left-hand side sum)?
9. $1^{3}+2^{3}+\cdots+(m-1)^{3}+m^{3} \equiv m^{3}+\left(1+(m-1)^{3}\right)+\cdots \equiv 0(\bmod m)$, when $2 \nmid$ $m ; \equiv(m / 2)^{3}(\bmod m)$, when $2 \mid m$. It holds when $2 \nmid m$ or $4 \mid m$, and does not hold when $2 \mid m, 4 \nmid m$.