m=1*2*3*4*5*…*19*20, what is the sum of all prime factors of m.
m=1*2*3*4*5*…*19*20，m所有质因数的和是多少．
<gadget id="calculator">2 + 3 + 5 + 7 + 11 + 13 + 17 + 19</gadget>
<output>77</output>

<result>77</result>