Answer
520 is not perfect because:
1 + 2 + 4 + 5 + 8 + 10 + 13 + 20 + 26 + 40 + 52 + 65 + 104 + 130 + 260 ≠ 520
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Answer
520 is not perfect because:
1 + 2 + 4 + 5 + 8 + 10 + 13 + 20 + 26 + 40 + 52 + 65 + 104 + 130 + 260 ≠ 520