123456 is not correct

Since $b, d, f$ are even numbers ( $2, 4, 6$ ) and $e$ is $5$ (because it can't be $0$ ), $a$ and $c$ are $1$ and $3$ in some order. $3\mid a+b+c$ , so $b$ has to be $6$ . If $d=4$ , then even $c=1$ or $c=3$ , $4\not\mid \overline{cd}$ , $\overline{abcd}$ , so $d=2$ . From that there are two possible solutions left, which are both correct:

Solution 1: $\overline{abcdef}=163254$

Solution 2: $\overline{abcdef}=361254$