Fatto generale: 664 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 664 is a value of n so that n(n+7) is a palindrome.
Trivia: 664 is an unremarkable number.
Data storica: October 25th is the day in 1147 that the Portuguese, under Afonso I, and Crusaders from England and Flanders conquer Lisbon after a four-month siege.