220 = 1 × 2 × 34 + 56 + 7 + 89
220 = 9 × 8 + 76 + 5 + 4 + 3 × 21
220 = 0^7 + 1^9 + 2^5 − 3^8 + 4^6 + 5^2 + 6^3 + 7^4 + 8^0 + 9^1
220 divides 21^2 - 1.
220 = (1 + 1) × (111 − 1)
Numbers k such that k^4 + 1 is prime.
Numbers k such that k^2 divides 9^k - 1
Amicable number
Factors: 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220
Two hundred twenty
Representations, Binary to Hexadecimal:
11011100_2
22011_3
3130_4
1340_5
1004_6
433_7
334_8
264_9
190_11
164_12
13c_13
11a_14
ea_15
dc_16
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Undergraduate Texts in Mathematics
Graduate Studies in Mathematics
