Dynamically generated means that it is database driven. More info on that: It is a multi-parent-child database. Countries X States X Cities X Institutions in the widget industry X other info X even more info = 5 milion plus pages.
I agree, but this site has had between 87K to 100K+ pages indexed for years now. I never thought it would be fully indexed, nor even get 100K pages indexed when I first built it... but my point is that it was for years.
Also the result from "site:mydomain.com" has me a little puzzled -- "Results 1 - 21 of about 5,510,000 from mydomain.com for . (0.25 seconds) " G reports my site having 5,510,000 pages but even with supplemental results past the 21, I can only get to 31 pages. When G reported I had 100K pages, I could get to ALL 100K pages. Why only 31 now?