General fact: 867 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 867 is the number of graphs with 8 vertices that have chromatic number 5.
Trivia: 867 is an unremarkable number.
Historical date: May 16th is the day in 1960 that Theodore Maiman operates the first optical laser, at Hughes Research Laboratories in Malibu, California.