Hecho general: 9912 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 9912 is the number of graceful permutations of length 14.
Trivia: 9912 is a boring number.
Fecha histórica: February 19th is the day in 197 that Emperor Septimius Severus defeats usurper Clodius Albinus in the Battle of Lugdunum, the bloodiest battle between Roman armies.