Simplify as much as possible:
504 = 2 x 252
252 = 2 x 126
126 = 2 x 63
63 = 3 x 21
21 = 3 x 7
7 * 3 * 3 * 2 * 2 * 2 is your prime factorization, or 7 * 3² * 2³
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