googillion

A googillion is an astronomer’s "largest number possible" synonym for everyday real-world objects that are unknown and unknowable. Example, from string theory, how many strings are there in the universe? The answer is a googillion. Although the real answer is a specific number at any given point in time, the number is both an unknown and unknowable largest number.
Since any largest number can become larger simply by adding the number one, all the strings in the universe plus one is also a googillion.
source: Wikipedia, the free encyclopedia, Large numbers