title: Finding all divisors using math library
body: <p>I'm trying to write the most efficient code to find divisors of number N:</p>
  
  <p>Here is my code:</p>
  
  <pre><code>def divisors(n):
      divs = set()
      for i in range(1, int(math.sqrt(n)) + 1):
          if N % i == 0:
              divs.add(i)
              divs.add(int(n/i))
      return divs
  </code></pre>
  
  <p>The problem is when I put 5 it gives me <code>{1, 2, 5}</code> when 2 is not divisor of 5</p>