Fait mathématique: 8669 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 18 stamps.
Culture générale: 8669 is a boring number.
Date historique: September 25th is the day in 1555 that the Peace of Augsburg is signed in Augsburg by Charles V and the princes of the Schmalkaldic League.