Do you know that Google derived its name from a number called googol? The number googol is equivalent to 10^100 which is equal to number 1 followed by 100 zeros.
Googolplex is equivalent to 10^googol. This is considered to be the largest number in the universe. Carl Sagan, once said that even if you were to use all the particles in the universe to represent the number googolplex, we will still run out of the particles to represent it. In in other words, there is no room or space available in the universe to represent the number Googolplex!!