Fatto generale: 86563 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 86563 is an uninteresting number.
Trivia: 86563 is an unremarkable number.
Data storica: December 31st is the day in 535 that Byzantine General Belisarius completes the conquest of Sicily, defeating the Ostrogothic garrison of Syracuse, and ending his consulship for the year.