I didn’t know this! From a recent XKCD comic:
This is correct! The value of epi – pi is 19.999099979 (plus a trailing infinite list of numbers). I strongly suspect this is just a coincidence — after all, why not pie – pi (19.317565) or pie – e (19.740875)? If you pick enough numbers, one of them is bound to come out near an integer coincidentally. Hoagland bases his whole "Face on Mars" nonsense on this numerology fallacy.
It’s funny how coincidences seem like more than they are. Our brains are wired for that sort of thing.