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A - Odd vs Even Editorial by evima
When \(N = 2^d \times a\) (\(a\): even), the set of the divisors of \(N\) is:
\(\left\{2 ^ i \times j \middle| 0 \leq i \leq d, j\text{ is a divisor of }a \right\}\)
Thus, if \(N\) has \(m\) odd divisors, it has \(dm\) even divisors.
Therefore, the answer is:
- Even, if \(N\) is divisible by \(4\);
- Same, if \(N\) is divisible by \(2\) but not by \(4\);
- Odd, if \(N\) is not divisible by \(2\).
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