Answer
Please see the work below.
Work Step by Step
We know that
$Length=\frac{3.72A^{\circ}}{1 \space Na \space atom}\times 2.619\times 10^{22}Na\space atoms=9.742\times 10^{22}A^{\circ}$
Now $9.742\times 10^{22}A^{\circ}\times \frac{10^{-10}}{1A^{\circ}}\times \frac{1mile}{1.609\times 10^3}=6.06\times 10^9 miles$
