ART

21

21 = 3 * 7, F8 8th Fibonacci number

221 - 1 =  7 * 7 * 127 * 337

21 = 4!− 4 + 4 ÷ 4 = (44 − √4) ÷ √4

1021 - 1 = 3 * 3 * 3 * 37 * 43 * 239 * 1933 * 4649 * 10838689

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