8. For a positive integer $n$, let the sum of its digits be denoted as $s(n)$, and the product of its digits as $p(n)$. If $s(n)+p(n)=n$ holds, then $n$ is called a coincidence number. The sum of all coincidence numbers is $\qquad$ .
Obviously, there is no 1-digit coincidence number; let the 2-digit coincidence number be $\overline{a b}$, then $a+b+a b=10 a+b$ $\Rightarrow a b=9 a \Rightarrow b=9$, that is, $\overline{a b}=19,29,39,49,59,69,79,89,99$;
Let the 3-digit coincidence number be $\overline{a b c}$, then $a+b+c+a b c=100 a+10 b+c \Rightarrow a b c=99 a+9 b$ $\geqslant 99 a \Rightarrow b c \geqslant 99$, contradiction; Similarly, it can be proved that there are no other digit coincidence numbers.
Therefore, the sum of all coincidence numbers is $9.59=531$.