Fait mathématique: 2659 is the maximum value of n so that there exist 5 denominations of stamps so that every postage from 1 to n can be paid for with at most 13 stamps.
Culture générale: 2659 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Date historique: April 12th is the day in 1937 that Sir Frank Whittle ground-tests the first jet engine designed to power an aircraft, at Rugby, England.