I1.3 If $C$ is the sum of all positive factors of $B$, including 1 and $B$ itself, find the value of $C$.
$$
\begin{array}{l}
108=2^{2} \cdot 3^{3} \\
C=\left(1+2+2^{2}\right) \cdot\left(1+3+3^{2}+3^{3}\right)=7 \times 40=280
\end{array}
$$

Remark: Original version: 若 $C$ 是 $B$ 的所有因子之和... If $C$ is the sum of all factors $\cdots$ Note that if negative factors are also included, then the answer will be different.