The Hitchhiker's number is equal to \(2^{276,709}\).^{[1]} It was coined in The Hitchhiker's Guide to the Galaxy, a comedy science fiction novel by Douglas Adams. Adams jokingly gave this number as the reciprocal of the probability that a spaceship would pick someone up in the cosmos during a period of 30 seconds.

The number contains exactly \(83,298\) digits, placing it just under a googolgong, and larger than \(6 \uparrow\uparrow 3\). This makes it small enough to compute and store the full decimal expansion on modern computers. Its decimal expansion starts with \(511,764,533,051,720,592,987,157,233,954,...\) and ends with \(...,483,635,033,435,620,175,872,379,584,512\).

It is the largest googolism which is a power of 2 with an exponent coprime to 6.