Hecho matemático: 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 number for which we're missing a fact (submit one to numbersapi at google mail!).
Fecha histórica: June 4th is the day in 1989 that the Tiananmen Square protests are violently ended in Beijing by the People's Liberation Army.