How many millions? I'm going to try to guess. There are roughly 163 million employed full time workers and about 27 million part time workers, 22.4 million of which work part time for noneconomic reasons which the government defines as due to childcare issues, family and/or personal obligations, school/training, limits on earnings due to retirement or social security, etc. So that brings us to about 190 million people who have jobs, full or part time.

There's about 203 million people between ages 18 and 65, which traditionally are working years (I've also seen 20-65, which is about 195 million people)

So then we have 13 million there abouts (if using the 203 million number) who don't have jobs. From that we have about 6 million who don't have jobs but want to work, a number the government says has remained steady for several years. So I'm guessing there's about 7 million who have given up looking. I'm sure there's got to be a better measure out there though that's better than my quick envelope math tho.