According to this page:
http://ismacs.net/singer_sewing_mach...s-200-299.html
and if I am reading it correctly, this machine was said to be pale turguoise and made from 1955-64. I could not find any serial numbers for those machines. I wonder if the "F" stands for featherweight (could the "A" actually be a "W"?), the 221 stands for ... well ... 221 and the last three numbers might mean it was the 748th one made??? I am only magically speculating so hopefully someone with a whole lot more intelligence than I will be able to help you out.