Charles Ellicott Commentary Numbers 1:46

"even all they that were numbered were six hundred thousand and three thousand and five hundred and fifty." — Numbers 1:46 (ASV)

Six hundred thousand and three thousand and five hundred and fifty. —It is obvious that the odd numbers were not reckoned. In Numbers 11:21, as in Exodus 12:37, the whole number is reckoned roughly at six hundred thousand.