Fatto generale: 86581 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 86581 is a boring number.
Trivia: 86581 is an unremarkable number.
Data storica: January 18th is the day in 1911 that Eugene B. Ely lands on the deck of the USS Pennsylvania stationed in San Francisco harbor, the first time an aircraft landed on a ship.