527

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?