Letting scripture interpret scripture, the sons of Korah tell us what Nephilim are. Nephilim are defined in Genesis 6:4 as men of renown. So are the sons of Korah defined in numbers 16:2. In Hebrew, this is ish shem, which literally means men (people) who are trying to make a name for themselves, meaning wanting authority not granted by Yahweh. Shabbat shalom.