Fait mathématique: 6745 is the maximum value of n so that there exist 4 denominations of stamps so that every postage from 1 to n can be paid for with at most 25 stamps.
Culture générale: 6745 is an unremarkable number.
Date historique: June 19th is the day in 1953 that Julius and Ethel Rosenberg are executed at Sing Sing, in New York.