General fact: 1517 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 1517 is the product of two consecutive primes.
Trivia: 1517 is an unremarkable number.
Historical date: February 25th is the day in 1948 that the Communist Party takes control of government in Czechoslovakia and the period of the Third Republic ends.