12. Let $N=34 \times 34 \times 63 \times 270$. Then the ratio of the sum of all odd factors of $N$ to the sum of all even factors of $N$ is ( ).
(A) $1: 16$
(B) $1: 15$
(C) $1: 14$
(D) $1: 8$
(E) $1: 3$
12. C.

Notice that, $N=2^{3} \times 3^{5} \times 5 \times 7 \times 17^{2}$, for each odd factor $n_{i}(i=1,2, \cdots, 72)$ of $N$, there are three even factors $2 n_{i}, 4 n_{i}, 8 n_{i}$ corresponding to it, so the required value is
$$
\frac{\sum_{i=1}^{72} n_{i}}{\sum_{i=1}^{72}\left(2 n_{i}+4 n_{i}+8 n_{i}\right)}=\frac{\sum_{i=1}^{72} n_{i}}{14 \sum_{i=1}^{72} n_{i}}=\frac{1}{14} .
$$