To calculate the required reserves based on the reserve requirement set by the central bank, you can use the formula:
\[ \text{Required Reserves} = \text{Deposit} \times \text{Reserve Requirement} \]
In this case, the deposit is R20641 and the reserve requirement is 67% (or 0.67 in decimal form).
Now we can perform the calculation:
\[ \text{Required Reserves} = R20641 \times 0.67 \]
\[ \text{Required Reserves} = R13829.47 \]
Therefore, the required reserves are R13829.47.