General fact: 789 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 789 is a boring number.
Trivia: 789 is an uninteresting number.
Historical date: February 27th is the day in 1626 that Yuan Chonghuan is appointed Governor of Liaodong, after he led the Chinese into a great victory against the Manchurians under Nurhaci.