Mathematical fact: 5629 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 16 stamps.
Trivia: 5629 is an unremarkable number.
Historical date: May 30th is the day in 1948 that a dike along the flooding Columbia River breaks, obliterating Vanport, Oregon within minutes.