Fatto generale: 8670 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 8670 is a value of n for which n!!.
Trivia: 8670 is an unremarkable number.
Data storica: September 26th is the day in 1997 that an earthquake strikes the Italian regions of Umbria and the Marche, causing part of the Basilica of St. Francis at Assisi to collapse.