One (1) Googol

= 10 ^ 100
(i.e. a one followed by 100 zeros.)
10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

Wikipedia: Googol