general_fact: 52 is the number of white keys (notes in the C major scale).
math_fact: 52 is the 5^{th} Bell number.
trivia: 52 is the number of letters in the English alphabet, if majuscules are distinguished from minuscules.
historical_date: February 21st is the day in 1972 that President Richard Nixon visits the People's Republic of China to normalize Sino-American relations.