Thematic Bible: Of the firstborn

And for the redemption of the 273 firstborn males of the Israelites who exceed the number of the Levites, collect five shekels for each one individually; you are to collect this amount in the currency of the sanctuary shekel (this shekel is twenty gerahs). And give the money for the redemption of the excess number of them to Aaron and his sons." read more.
So Moses took the redemption money from those who were in excess of those redeemed by the Levites. From the firstborn males of the Israelites he collected the money, 1,365 shekels, according to the sanctuary shekel. Moses gave the redemption money to Aaron and his sons, according to the word of the Lord, as the Lord had commanded Moses.

The firstborn of every womb which they present to the Lord, whether human or animal, will be yours. Nevertheless, the firstborn sons you must redeem, and the firstborn males of unclean animals you must redeem. And those that must be redeemed you are to redeem when they are a month old, according to your estimation, for five shekels of silver according to the sanctuary shekel (which is twenty gerahs).