If you're working with enough stitches, you don't have to divide them at all. Just join and go. You'll be knitting a continuous spiral until you're either done or have to divide the stitches for one of the small-diameter techniques.
But since you've specifically mentioned dividing stitches, I'll assume you've got to the point where the work is too small to reach around the circular. And yes, you can just divide the number of sts by 2, and put that many sts on each needle. That's helpful for keeping track of where you are, but if you don't have the same number on each side it doesn't hurt anything. Which is helpful when you have to divide 9 sts .