what is 9223372036854775806!

I don't believe this has an actual computable answer... even if you enter it into a calcuator the value is too high to display. By hand is a whole other matter.

Using Stirling's Formula:

what is 9223372036854775806! ==log(log(10^20.2327791))

If you are going to use Stirling's approximation, then you got it backwards!

what is 9223372036854775806! ==10^(10^(10^1.306055539958))