12 May 07
Sure this number doesn't tell anything about the size, but for anyone who's interested... i googled the number of atoms, and this is the first result:
http://www.madsci.org/posts/archives/oct98/905633072.As.r.html
But if you take the number of atoms in a human compared to the number of atoms in the universe, we would be well under half way between an atom and the universe, and as jirakon said, that doesn't include empty space. So to sum up, we're really little.