Question: What is the minimum number...

Solve using Maple:Twenty-one pirates are dividing their horde of gold dubloons. Since they are a
democratic outfit, they first try to divide the coins evenly, but they find there are 19
coins left over. The “discussion” about how to divide the remaining coins results in
only 16 pirates still needing to divide the horde (the remaining five went to a place
where you can’t bring money or anything else with you). The redivision among
16 pirates leaves 1 coin left over, and three of the pirates make a grab for it. These
three find themselves to bemissing their hands after this attempt, and the remaining
thirteen pirates decide to divide the share among themselves, leaving the handless
ones with nothing. Fortunately, the horde divides evenly among the thirteen. What
is the minimum number of coins in the horde?

can anybody give some hints how to start ..?