General fact: 52 is the number of letters in the English alphabet, if majuscules are distinguished from minuscules.
Mathematical fact: 52 is the 5^{th} Bell number.
Trivia: 52 is the number of cards in a standard deck of playing cards, not counting Jokers or advertisement cards.
Historical date: February 21st is the day in 1613 that Mikhail I is elected unanimously as Tsar by a national assembly, beginning the Romanov dynasty of Imperial Russia.