Fatto matematico: 990 is a triangular number that is the product of 3 consecutive integers.
Trivia: 990 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: September 16th is the day in 1966 that the Metropolitan Opera House opens at Lincoln Center in New York City with the world premiere of Samuel Barber's opera, Antony and Cleopatra.