The homework for last week was a little harder than the prior one:
- Let n be a positive integer, . Prove that the sum of the divisors of n is a multiple of 24.
- Let N = 210 × 39 × 58. Calculate:
- the number of divisors of N;
- the sum of all divisors of N;
- the number of i modulo N which are coprime to N.
- is a cube;
- is a square.