Ok, so if it ends with a zero, that means it is divisible by ten. This means the number is divisible by both 5 and 2.

The sum of the digits is also divisible by 3, so that means it is divisible by 3.

Because it is divisible by 3 and 2, it is also divisible by 6.

6, 3, 5, 2, are the only ones that can necessarily divide it, so your answer is 4.