How many atoms (or molecules, if that's easier) are in an average human cell?

"let's assume an average adult weighs 70 kilograms. Be sure to keep in mind that the following numbers are based on the number of atoms, not percent of body weight (by weight we are mostly oxygen). A 70 kg body would have approximately 7*10^27 atoms."
http://education.jlab.org/qa/mathatom_04.html
"It is estimated that the
average human adult body contains about 10 trillion cells"
http://www.cdli.ca/CITE/bw_cells.pdf

I'm pretty sure they are using the American name of trillion and not the British name of a trillion, thus they mean 10^12. So (7*10^27)/(10^12) = 7*10^15 atoms per human cell. Thats 7 with 15 0s following, 7 thousand billion (7 quadrillion in US usage).

An average human cell is about 10 micrometers in size.
There are about 7 quadrillion atoms in an average human cell. If the cell were a cube in shape, then there would be approximately 191,000 atoms along each side.

To help visualize this consider that a grain of sand is anywhere from 2 to .05 millimeters in diameter. If a cube shape grain of sand 1 mm on each side were hollow then you could fit a million average human cells into the grain of sand.

If a human cell were as large as this grain of sand, then the human would be over 600 feet tall. He would stand as tall as a 50 story skyscraper. Godzilla on the other hand is only somewhere between 160 and 260 feet tall depending upon which movie you are watching.

If an atom were as large as the grain of sand, then a cube shaped human cell would be 191 meters on each side, or just over two football fields (600 feet) in length on each side and 50 stories high.
(all estimates approximate)

There are aprox 10^9 (a billion) atoms on the point of a standard hospital needle point, a human cell is a little bigger than that so I would guess 10^10 (10 billion)