John Gill Commentary 2 Chronicles 17:15

"and next to him Jehohanan the captain, and with him two hundred and fourscore thousand;" — 2 Chronicles 17:15 (ASV)

And next to him was Jehohanan the captain. Being of the same rank as to office, but having a lesser number of men under him, it may respect not any kind of subordination, only nearness of place, as the Targum says, "he that encamped next to him".

And with him two hundred and fourscore thousand; which number was but 20,000 less than the former.