Fatto generale: 1511 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1511 is an unremarkable number.
Trivia: 1511 is an uninteresting number.
Data storica: 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.