Fatto matematico: 7713 is a value of n for which 4n and 9n together use each digit exactly once.
Trivia: 7713 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: February 11th is the day in 1990 that Nelson Mandela is released from Victor Verster Prison outside Cape Town, South Africa after 27 years as a political prisoner.