How many died in the plague after Korah's rebellion, besides those who died because of Korah?

Answer: 14,700

Aaron's incense halted the plague as he stood between the living and the dead, but 14,700 had already died (KJV: fourteen thousand seven hundred).

“He stood between the living and the dead, and the plague was halted. But those who died from the plague numbered 14,700, in addition to those who had died on account of Korah.”— Numbers 16:48-49 (BSB)