Fatto matematico: 634 is a number n whose 5^{th} root has a decimal part that begins with the digits of n.
Trivia: 634 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: September 25th is the day in 1959 that Solomon Bandaranaike, Prime Minister of Sri Lanka is mortally wounded by a Buddhist monk, Talduwe Somarama, and dies the next day.