Fatto generale: 9964 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 9964 is a boring number.
Trivia: 9964 is an uninteresting number.
Data storica: April 12th is the day in 1204 that the Crusaders of the Fourth Crusade breach the walls of Constantinople and enter the city, which they completely occupy the following day.