Fait mathématique: 5673 is the smallest number whose 6^{th} power starts with 5 identical digits.
Culture générale: 5673 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: July 13th is the day in 1919 that the British airship R34 lands in Norfolk, England, completing the first airship return journey across the Atlantic in 182 hours of flight.