Now Korah, son of Izhar son of Kohath son of Levi, betook himself, along with Dathan and Abiram sons of Eliab, and On son of Peleth descendants of Reuben.
Korach was a reincarnation of Kayin.
Interestingly, the Torah lists Korah’s genealogy only up to Yaakov, because Yaakov had foreseen his descendant Korach’s evil ways and had prayed that he wouldn't be associated with him.
Most of Korach’s followers came from the tribe of Reuven, a tribe which encamped near Korach’s camp. Hence, we learn from here to ensure we have good neighbors.
A “cute” gematria: There are two sides (“tzad”) to a fight. If both sides would listen to each other, we would have a better “perception” of the issue (the numerical value of tzad + tzad = “pike’ach/perceptive”). Furthermore, Korach was “perceptive” and Moshe was “perceptive.” If Korach would have listened to Moshe, there would have been “peace” (the numerical value of pike’ach + pike’ach = “shalom/peace”). Too bad Korach wasn’t willing to listen!