What's Special About This Number?

19 is the maximum number of 4th powers needed to sum to any number.: "It's been said that 3 is the magic number, but really, what makes the curvy digit so special? We now have the answer to that question (and other numerical mysteries) thanks to this wonderfully interesting site. Turns out the number 3 is the "number of spatial dimensions in which we live." Okay, so that's a somewhat mystifying fact, but what about, say, the number 171? Well, that would be a palindromic triangular number, of course. And everyone knows that when the discussion touches on Carmichael numbers, 561 is the smallest one around. This site is filled with thousands of distinctive facts about numbers with links to definitions of obscure terms. There will be a pop quiz, so don't forget that 1078 is the number of lattices on 9 unlabeled nodes. "