What comes next in this series?

0, 1, 2, 720!, ?

In math, the exclamation mark is a factorial, which is the product of every whole number from 1 to n.

For example, five factorial is written 5! = 1x2x3x4x5 = 120. By definition 0! = 1.

So 720! = 1x2x3x4x...718x719x720, which is a very large number.