Question 353100
The number 2^48 - 1 divisible by two numbers between 60 and 70. Their sum is:

(a) 124 (b) 128  (c) 132 (d) 136  (e) None of the above


http://www.wolframalpha.com/input/?i=factor+%282%5E48%29-1
(used factor 2^48 - 1 to get factors)


prime factorization: 3^2 * 5 * 7 * 13 * 17 * 97 * 241 * 257 * 673
this gives 768 divisors according to wolframalpha
here is the ones up to 105:
1,3,5,7,9,13,15,17,21,35,39,45,51,63,65,85,91,97,105


the 2 numbers between 60 and 70 are 63 and 65
63 + 65 = 128, answer is (b) 128