I'm very sure #1, 4, 13, 16, and 20 are cockerels. With those combs at 5 weeks I have no doubts.
I strongly suspect #9, 11, and 17 to be cockerels based on the red shoulder patches. That's usually male specific coloration.
#12 I am 100% sure is a pullet because she's partridge and has the female color pattern. A male would have black breast feathers. She's very pretty!
Based on comb development, I believe #2, 3, 6, 7, 8, 10, 15, 18, 19, and 21 are most likely pullets.
#5 and 14 I'm not sure about yet, they could go either way.
#5 doesn't have enough comb development to make me think definitely male but more than the chicks I believe are pullets.
#14 has the comb development I would expect from a pullet, but the red on the wings may or may not be male specific coloration. I'm leaning pullet, but it could be a slow developing cockerel.
11-13 pullets to 8-10 cockerels is not terrible odds though. They're all adorable.