General fact: 4040 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 4040 is an enneagonal pyramidal number.
Trivia: 4040 is an uninteresting number.
Historical date: January 22nd is the day in 1877 that Arthur Tooth, an Anglican clergyman is taken into custody after being prosecuted for using ritualist practices.