Hecho general: 7884 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 7884 is a value of n for which 2n and 5n together use each digit exactly once.
Trivia: 7884 is an unremarkable number.
Fecha histórica: August 1st is the day in 1966 that Charles Whitman kills 16 people at The University of Texas at Austin before being killed by the police.