You got the wrong numbers for the 4004! The 4004 had just 2300 transistors in a 12 mm^2 area. So, today you can fit 3*10^8 * 12 = 3.6*10^9 transistors in that area, or 1.5 million 4004s, or 650 4004s in the area of the old transistor.
Thanks for the correction, I was looking at the 286, not the 4004! Not sure how I managed to get the wrong chip... Though someone mentioned the 286 in a comment below, so I guess I muddled that in.
