The Number of the Beast is a science fiction novel by Robert A. Heinlein published in 1980 (ISBN 0-44-913070-3).

The book is a series of diary entries by each of the 4 main characters, Captain Zebadiah , programmer Deety and her math professor father, and an off-campus socialite. The odd foursome dash off in Zeb's sports car spaceship, outfitted with the professor's hyperspace drive, into various fictional universes. There is plenty of sex, rivalry, and even a trip to Oz.

In the novel, the biblical number of the beast turns out to be, not 666, but , an unimaginably large, 36306-digit number (6↑↑3 in Knuth's up-arrow notation) which is the number of parallel universes accessible to the protagonists.

The novel lies somewhere between parody and homage in its deliberate use of the style of the 1930's pulp novels. Many of the plot lines and characters are derived directly from the pulps, as directly referenced by the first line of the novel:

"He's a Mad Scientist and I'm his Beautiful Daughter ." --Deety

Number of the Beast contains many in-jokes and references. For instance, the name of every villain is an anagram of a name or pen name of Robert or Virginia Heinlein . The book is generally held to be a contender for Heinlein's worst novel, although one school of thought holds that it is an extended demonstration of Heinlein's knowledge of writing using bad examples.

In this book Heinlein introduced the concept called "pantheistic solipsism" or "world-as-myth" -- the theory that universes are created by the act of imagining them, so that somewhere even fictional worlds (Oz is one of the examples Heinlein uses) are real.

Near the end, this book is connected to Time Enough for Love, and through it to several others of Heinlein's later works.

Editions

• July 12, 1980, Ballantine Books, paperback, 511 pages, ISBN 0449900401
• December 12, 1980, Ballantine Books, paperback, ISBN 0449900193
• May 12, 1982, Fawcett, paperback, ISBN 0449144763
• September 12, 1986, Fawcett, paperback reissue edition, 512 pages, ISBN 0449130703