Fatto generale: 7880 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 7880 is the maximum value of n so that there exist 4 denominations of stamps so that every postage from 1 to n can be paid for with at most 26 stamps.
Trivia: 7880 is an unremarkable number.
Data storica: July 28th is the day in 1540 that Thomas Cromwell is executed at the order of Henry VIII of England on charges of treason.