Mathematical fact: 70573 is an uninteresting number.
Trivia: 70573 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Historical date: March 21st is the day in 1935 that Shah Reza Pahlavi formally asks the international community to call Persia by its native name, Iran, which means 'Land of the Aryans.