Fatto generale: 91715 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 91715 is an unremarkable number.
Trivia: 91715 is an unremarkable number.
Data storica: February 8th is the day in 1971 that South Vietnamese ground troops launch an incursion into Laos to try to cut off the Ho Chi Minh trail and stop communist infiltration.