The task is to find x. (Source https://free.ultimaiq.net/nse.htm)
123456, x , 93332736, 3359978496
The answer is
The reason is:
To get from one number to the next, it is multiplied by the sum of its digits. So $123456$ is multiplied by $1+2+3+4+5+6=21$ to get $2592576$. This is multiplied by $2+5+9+2+5+7+6=36$ to get the next number $93332736$, and so on.