Is there an efficient way to work out how many factors a large number has?
15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?
Find the number which has 8 divisors, such that the product of the divisors is 331776.
What part of the powers of 3 and 7 tell you that it is divisible by 10?