General fact: 81915 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 81915 is an uninteresting number.
Trivia: 81915 is a boring number.
Historical date: April 10th is the day in 837 that Halley's Comet and Earth experienced their closest approach to one another when their separating distance equalled 0.0342 AU (3.2 million miles).