To find out how many bytes of storage each customer can use, we need to divide the total storage by the number of customers:
\[ \text{Bytes per customer} = \frac{1.326 \times 10^{13} \text{ bytes}}{2.6 \times 10^{4} \text{ customers}} \]
First, we can perform the division of the coefficients:
\[ \frac{1.326}{2.6} \approx 0.510 \]
Now, we divide the powers of 10:
\[ \frac{10^{13}}{10^{4}} = 10^{13-4} = 10^{9} \]
Now, we multiply the coefficient by the power of ten:
\[ 0.510 \times 10^{9} \]
To express this in proper scientific notation, we need to adjust it to have one non-zero digit to the left of the decimal:
\[ 0.510 \times 10^{9} = 5.10 \times 10^{8} \]
Thus, the amount of storage available per customer is
\[ \boxed{5.10 \times 10^{8}} \text{ bytes} \]