Numbers 1:19-21

19 Moshe counted them in the Sinai Desert, just as ADONAI had ordered him.

20 [19] (ii) The men twenty years old and over who were subject to military service were recorded by name, family and clan, starting with the descendants of Re’uven, Isra’el’s firstborn. Here are the totals: —

21 Descendants of Re’uven — 46,500 —