Fatto generale: 86523 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 86523 is an uninteresting number.
Trivia: 86523 is an uninteresting number.
Data storica: November 21st is the day in 1386 that Timur of Samarkand captures and sacks the Georgian capital of Tbilisi, taking King Bagrat V of Georgia captive.