Mathematical fact: 1617 is the maximum value of n so that there exist 6 denominations of stamps so that every postage from 1 to n can be paid for with at most 9 stamps.
Trivia: 1617 is a boring number.
Historical date: June 4th is the day in 2001 that Gyanendra, the last King of Nepal, ascends to the throne after the massacre in the Royal Palace.