9514 1404 393
Answer:
203
Explanation:
The prime factorization is ...
132 = 2·2·3·11
The exponents of these factors are 2, 1, 1, so the number of divisors is ...
(2+1)(1+1)(1+1) = 12
Those divisors are ...
1, 2, 3, 4, 6, 11, 12, 22, 33, 44, 66, 132
The proper factors are all but the first and last of these. Their sum is ...
2 +3 +4 +6 +11 +12 +22 +33 +44 +66 = 203
The sum of proper factors of 132 is 203.