Hecho general: 9528 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 9528 is an unremarkable number.
Trivia: 9528 is an unremarkable number.
Fecha histórica: January 31st is the day in 1891 that the first attempt at a Portuguese republican revolution breaks out in the northern city of Porto.