In the Hitchhiker's Guide to Galaxy science fiction series, a supercomputer named Deep Thought spends 7.5 million years computing the Answer to the Ultimate Question of Life, the Universe, and Everything, arriving at the answer 42. This has earned 42 a place in popular culture, in addition to the shorter name Meaning of Life. A larger number coined in the book — albeit a less culturally significant one — is the Hitchhiker's number.
- 42 is an even composite number.
- It is the third primary pseudoperfect number.
- 42 is the sum of the first 6 positive even numbers.
- In Greek-based number-naming systems, 42 is associated with prefix "dutetraconta-", and with prefix "duoquadraginti-" in Latin systems.
- André Joyce calls this number Lok or Tien grow. 
- There are OEIS A001174(4) = 42 oriented graphs on four unlabeled nodes.
- In the Major League Baseball, the jersey number 42 has been retired league-wide for Jackie Robinson.