1e is a way to show big numbers with a few characters. The e means exponent.
1e means 10^.
whatever number after is what goes after the ^.
so 1e+36 is 10^36.

As Lua 5.1 number is actually a double, the highest number you can store without makining it infinity is approximately 2 ^ 1024 or 1.7976931348623157e+308, though the maximum safe integer a double can store is 2 ^ 53 or 9 007 199 254 740 992.

That’s for long long int (or int64), not double, as all numbers in Lua 5.1 are double. Also there’s bignum/bigint that can bypass this.