527 = 17 x 31.
527 is the smallest number n for which there do not exist four smaller numbers so that a1! a2! a3! a4! n! is square.
527 is 252 in base 15.
527 is a brilliant number (A078972). It is a semiprime whose prime factors have the same number of digits.
Section 527 of the U.S. Tax Code regulates soft money political campaigning.
Source: What's Special About This Number?