Factors of 81

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What are the Factors of 81?

Answer

Factors of 81:

1, 3, 9, 27, 81

5 factors · 81 = 3⁴ · composite

Underlined — prime: 3 · 1 — neither prime nor composite · others — composite

Factor pairs of 81

3 pairs: 1 × 81 · 3 × 27 · 9 × 9

9 × 9 is a pair of one factor — that is why 81 has an odd number of factors, 5.

81 = 3⁴ → (4 + 1) = 5 factors: add 1 to each exponent and multiply.

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Prime Number Checker - Find out whether a given number is Prime or not
Prime Factorization - Prime Factorization Calculator
Prime Numbers List - List of all Prime Numbers - how many Prime numbers are between

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Factors Table

Number	Factors
66	1, 2, 3, 6, 11, 22, 33, 66
67	1, 67
68	1, 2, 4, 17, 34, 68
69	1, 3, 23, 69
70	1, 2, 5, 7, 10, 14, 35, 70
71	1, 71
72	1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
73	1, 73
74	1, 2, 37, 74
75	1, 3, 5, 15, 25, 75
76	1, 2, 4, 19, 38, 76
77	1, 7, 11, 77
78	1, 2, 3, 6, 13, 26, 39, 78
79	1, 79
80	1, 2, 4, 5, 8, 10, 16, 20, 40, 80
81	1, 3, 9, 27, 81
82	1, 2, 41, 82
83	1, 83
84	1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
85	1, 5, 17, 85
86	1, 2, 43, 86
87	1, 3, 29, 87
88	1, 2, 4, 8, 11, 22, 44, 88
89	1, 89
90	1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90
91	1, 7, 13, 91
92	1, 2, 4, 23, 46, 92
93	1, 3, 31, 93
94	1, 2, 47, 94
95	1, 5, 19, 95

FAQ

What are the Factors of 81?

Factors of 81: 1, 3, 9, 27, 81

How many factors does 81 have?

Number 81 has 5 factors

How many Factor Pairs does 81 have?

Number 81 has 3 factor pairs

Is 81 a prime or composite number?

Composite: 81 = 3⁴, so it has 5 factors — a prime has exactly two.

How many factors does 81 have excluding 1 and 81?

3: 3, 9 and 27.

Why does 81 have an odd number of factors?

81 is a perfect square: in the pair 9 × 9 the factor 9 pairs with itself, so the 5 factors are 2 pairs plus 9.