General fact: 12135 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 12135 is a boring number.
Trivia: 12135 is an uninteresting number.
Historical date: March 22nd is the day in 1975 that a fire at the Browns Ferry Nuclear Power Plant in Decatur, Alabama causes a dangerous reduction in cooling water levels.