input: Write a python function to calculate the sum of all divisors of a given number.
  assert calculate_sum_divisors(90) == 234
  assert calculate_sum_divisors(6) == 12
  assert calculate_sum_divisors(28) == 56
output: def calculate_sum_divisors(n):
      total = 0
      for i in range(1, n + 1):
          if n % i == 0:
              total += i
      return total