12. If the product of 3 prime numbers is 5 times their sum, then these 3 prime numbers are $\qquad$ .
12.7,5,2.

Let these 3 prime numbers be $x, y, z$, then
$$
5(x+y+z)=x y z \text{. }
$$

Since $x, y, z$ are prime numbers, we can assume $x=5$, then
$$
5+y+z=y z \text{. }
$$

Therefore, $(y-1)(z-1)=6$.
Assuming $y \geqslant z$, we have
$$
\left\{\begin{array} { l } 
{ y - 1 = 3 , } \\
{ z - 1 = 2 }
\end{array} \text { or } \left\{\begin{array}{l}
y-1=6, \\
z-1=1 .
\end{array}\right.\right.
$$

After verification, the 3 prime numbers are $7,5,2$.