John Gill Commentary Numbers 26:53

"Unto these the land shall be divided for an inheritance according to the number of names." — Numbers 26:53 (ASV)

Unto these the land shall be divided for an inheritance
That were numbered, and to none else:

according to the number of their names ;
and for this end was the number of them now taken, that the land might be equally divided among them; women and minors, or such as were under twenty years of age, had no share in it;

and even only those who were at that age at this time; so Jarchi says, it was not divided to any that were less than twenty years of age, even though they came to be full twenty before the division of the land; for they were seven years subduing it, and seven years dividing it, yet none took any part of it but these 601,730: nay, he says, if a man had six children they took but their father's part only.