Given a number N, find the even factor sum of the number N.

Example 1:
Input:
N = 30
Output:
48
Explanation:
Even dividers sum 2 + 6 + 10 + 30 = 48
Example 2:
Input:
N = 18
Output:
26
Explanation:
Even dividers sum 2 + 6 + 18 = 26
Your Task:
You don't need to read input or print anything. Your task is to complete the function evenFactors() which takes an integer N as input parameters and returns an integer, number of even factors of N.

Expected Time Complexity: O(sqrt(N))
Expected Space Complexity: O(1)

Constraints:
1 <= N <= 10^{9}

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