the sum of the divisors of 25.37.53.72  is

Any divisor of 25.  37.  53.  72  is of the form 2a  3b  5c  7d,  where 0  ≤  b  ≤  7,  0  ≤  c  ≤  3  and 0  ≤  d  ≤  2.   Thus, the sum of the divisors of 25.  37.  53.  72  is            (1  +  2  +...  +  25)  (1  +  3  +  ...  +  37) (1+5+52+53)  (1  +  7  +  72)            =(26−12−1) (38−13−1) (54−15−1) (73−17−1)          =(26−1) (38−1) (54−1) (73−1)48