Fatto generale: 4535 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 4535 is the number of unlabeled topologies with 7 elements.
Trivia: 4535 is a boring number.
Data storica: May 31st is the day in 1578 that Martin Frobisher sails from Harwich, England to Frobisher Bay, Canada, eventually to mine fool's gold, used to pave streets in London.