Check the properties of a positive integer to enter the number in the search box. If you input two numbers separated by a space, the properties of the pair like GCD are shown. If you separate two numbers by a comma, the sequences containing those numbers are listed.
81 = 3 × 3 × 3 × 3
| Factor | Count |
|---|---|
| 3 | 4 |
9
4.32674871092222446122832479886711...
0.0123456790123457
1010001
7
121
51
| Prime number | No |
| Hexagonal number | No |
| Perfect number | No |
| Deficient number | No |
| Abundant number | No |
| Mersenne number | No |
| Harshad number | Yes |
| Harmonic divisor number | No |
QR81 (sequence)
0
Properties of the number 81: 81 has 5 divisors. The divisors of 81 are 1, 3, 9, 27, 81 and the sum of them is 121. The factorization of 81 is 3 × 3 × 3 × 3. The square and cube of 81 are 6561 and 531441 respectively. The square root and cube root of 81 are 9 and 4.32674871092222446122832479886711.... The binary, octal, hexadecimal of 81 are 1010001, 121, 51. 81 is not a prime number, not hexagonal number, not perfect number, not deficient number, not Mersenne number, not Mersenne number, Harshad number, not harmonic divisor number.
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