The Prisoner is in the top ten best dramatic television series ever created, possibly number 1 of all time. This is, of course, largely down to Patrick McGoohan himself. It was his idea. It was his concept. It was a product of the '60s and a somewhat perfect mirror of western and world society of the day. It is many things, so many that it would require many books to elucidate. If you want to know why then watch a few (or all) episodes of Danger Man/ Secret Agent Man and then carefully watch all seventeen episodes of The Prisoner, back to front.
Then remember, Patrick MacGoohan spoke publicly almost not at all about the show, for the remainder of his life..... then watch this documentary.