Mathematical fact: 353 is the smallest number whose 4^{th} power can be written as the sum of four 4^{th} powers.
Trivia: 353 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Historical date: December 18th is the day in 1989 that the European Community and the Soviet Union sign an agreement on trade and commercial and economic cooperation.