Fatto generale: 676 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 676 is the smallest palindromic square number whose square root is not palindromic.
Trivia: 676 is an uninteresting number.
Data storica: November 6th is the day in 1977 that the Kelly Barnes Dam, located above Toccoa Falls Bible College near Toccoa, Georgia, fails, killing 39.