Finding out the number of atoms in the sun. This is the question from the text book: 


This is what I did, since it worked with all the previous questions (similar to this).

$$
\frac{\frac{4}{3}\pi(7*10^8)^3*1.4}{1.008} * 6.022*10^{23}
$$

This equals $1.2 *10^{51}$, but the answer is $1.2*10^{57}$

What have I done wrong? Thank you in advance.
The problem is that you did not include units with your numbers. If you had, you would have easily seen that you are multiplying $m^3$ and $cm^{−3}$ and coming up with 1 instead of 1000000.