Numbers 1:44-47

44These are those that were numbered, which Moses and Aaron numbered, and the princes of Israel, being twelve men: each one was for the house of his fathers. 45So were all those that were numbered of the children of Israel, by the house of their fathers, from twenty years old and upward, all that were able to go forth to war in Israel; 46Even all they that were numbered were six hundred thousand and three thousand and five hundred and fifty.

47But the Levites after the tribe of their fathers were not numbered among them.