http://mathforum.org/library/drmath/view/55402.html
Please double check your math:
Area of an oval is (w/2)*(h/2)*3.14
In our case, (.21/2)*(.16/2)*3.15 or 0.0263 sq miles.
I generated my own oval using autocad, different fomula.
I just did a more accurate to scale AutoCAD model and did an area take off using an oval .21 miles wide and .16 miles long. I got an area of 735,336 SF. So if I used approx 10SF per person i'm down to a capacity of 73,534 if the Oval is jammed full of moonbats.