Video still: Carl Sagan in his video on the Googolplex
The largest number with a word naming it is a “googolplex.” This is the equivalent of 10 to the power of a googol—or 10 to the power of 10100. The term googol was coined in 1938 by 9-year-old Milton Sirotta, the nephew of mathematician Edward Kasner. Kasner then extended the name to this larger number.
Watch a video by astronomer Carl Sagan about the googolplex, which is entertaining both because of its subject matter and because it looks so dated.