diff --git a/0021.py b/0021.py
index 1c1e86e..84c2516 100644
--- a/0021.py
+++ b/0021.py
@@ -5,19 +5,14 @@ import util
 
 target = 31626
 
-def sum_proper_divisors (nbr):
-    proper_divisors = util.divisors(nbr)[0:-1]
-
-    return reduce(lambda x, y: x + y, proper_divisors)
-
 r = 10000
 
 amicable_numbers = []
 
 for i in range(1, r + 1):
-    s = sum_proper_divisors(i)
+    s = util.sum_proper_divisors(i)
 
-    if (s != i and sum_proper_divisors(s) == i):
+    if (s != i and util.sum_proper_divisors(s) == i):
         amicable_numbers.append(i)
 
 
diff --git a/util.py b/util.py
index 43c68da..cc22845 100644
--- a/util.py
+++ b/util.py
@@ -1,6 +1,11 @@
 from collections import Counter
 from functools import reduce
 
+def sum_proper_divisors (nbr):
+    proper_divisors = divisors(nbr)[0:-1]
+
+    return reduce(lambda x, y: x + y, proper_divisors)
+
 def divisors(num):
     result = []
     def recurse(tuples, product = 1):