This number, a sum of 6 consecutive primes, has exactly 8 divisors.
Rem: Jeopardy style answer needs a question.
What is 56, Alex?
56 = 3+5+7+11+13+17 and is divided by 1,2,4,7,8,14,28,56.
I have no idea if 56 is unique.
If a,b,c . . . are the exponents of the prime factors of the sought for number then the number of divisors = (a+1)*(b+1)*(c+1) . . .
8 divisors require either (a,b,c) = (1,1,1) or (a,b) = (3,1). I checked for a cubic factor first since it looked easier.
Posted by xdog
on 2015-02-16 08:21:11