Fatto generale: 633 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 633 is the smallest number n whose 5^{th} root has a decimal part that begins with the digits of n.
Trivia: 633 is a boring number.
Data storica: September 24th is the day in 1906 that U.S. President Theodore Roosevelt proclaims Devils Tower in Wyoming as the nation's first National Monument.