The general rule of thumb is 4 square feet per chicken in the coop - and 10 square feet per chicken in the run. However, that's not set in stone.
My chickens go into the coop to (1) roost at night - and (2) during the day to lay their eggs. The rest of the time (all daylight hours) they spend in the run. So for a coop and run the sizes you listed, you could probably have more than 4 chickens - IF they'll spend most of their time in the run. Using the "rule of thumb" measurement, at 10 square feet per chicken, your run is big enough for 11 chickens, but the coop only has room for 4. I think you could have 5 or 6 chickens since your run is large in comparison to the coop.
I once had 7 chickens in a 3 x 6 coop - which was considerably less than the recommended 4 square feet per chicken. However, they had MORE than enough room in there. They roosted all huddled together on one roosting pole - leaving the other pole empty. Then as soon as it was daylight, they headed out to the run and stayed there (with 10+ square feet per chicken) all day. They go to the coop to lay an egg, and then head right back out to the run. There was never any issues with overcrowding.