Fatto matematico: 8506 is the number of isomers of C_{13}H_{26} without any double bonds.
Trivia: 8506 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: April 15th is the day in 1865 that Abraham Lincoln dies without regaining consciousness after being shot the previous evening by actor John Wilkes Booth.