Fait général: 4545 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 4545 is an unremarkable number.
Culture générale: 4545 is an uninteresting number.
Date historique: June 10th is the day in 2002 that the first direct electronic communication experiment between the nervous systems of two humans is carried out by Kevin Warwick in the United Kingdom.