Charles Ellicott Commentary Numbers 16:2

"and they rose up before Moses, with certain of the children of Israel, two hundred and fifty princes of the congregation, called to the assembly, men of renown;" — Numbers 16:2 (ASV)

And they rose up ... — that is, in rebellion.

Two hundred and fifty princes ... — It has been inferred from Numbers 27:3, where it is stated that Zelophehad, the Manassite, did not take part in the rebellion, that these princes, or chief men of the congregation, belonged to the other tribes of Israel as well as that of Levi. They are called Korah’s company because he was their leader, and it is probable from Numbers 16:8 that a large number of them belonged to the tribe of Levi.