The number 81090
81090 is a composite number with 48 divisors. Its prime factorisation is 2 × × 5 × 17 × 53. Divisors (48): 1, 2, 3, 5, 6, 9, 10, 15, 17, 18, 30, 34, 45, 51, 53, 85 … 81090.
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How to work it out
- 1
What is special about 81090: a Harshad number: divisible by its digit sum 18.
- 2
81090 is composite. Its prime factorisation is
- 3
The divisors add up to 227448; without 81090 itself that is 146358, so 81090 is abundant (146358 is more than 81090). Euler's totient φ(81090) = 19968 numbers up to 81090 share no factor with it.
- 4
The digits of 81090 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 63 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81090 = 2 \times 3^{2} \times 5 \times 17 \times 53 \]81090 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 48 |
| Sum of divisors | 227448 |
| Euler totient φ(n) | 19968 |
| Square | 6575588100 |
| Cube | 533214439029000 |
| Square root | 284.763059 (= 3√9010) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 63 |
| Scientific notation | 8.109 × |
81090 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand and ninety |
| Binary (base 2) | 10011110011000010 |
| Octal (base 8) | 236302 |
| Hexadecimal (base 16) | 13CC2 |
| Base 3 | 11010020100 |
| As time | 81090 seconds = 22 h 31 min 30 s |
Is 81090 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81090 ÷ 2 = 40545) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81090 ÷ 3 = 27030) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (81090 ÷ 5 = 16218) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (81090 ÷ 6 = 13515) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 2) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (81090 ÷ 9 = 9010) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (81090 ÷ 10 = 8109) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 6) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81090 a prime number?
No. 81090 = 2 × × 5 × 17 × 53, so it is divisible by 2.
What are the factors of 81090?
1, 2, 3, 5, 6, 9, 10, 15, 17, 18, 30, 34, 45, 51, 53, 85, 90, 102, 106, 153, 159, 170, 255, 265, 306, 318, 477, 510, 530, 765, 795, 901, 954, 1530, 1590, 1802, 2385, 2703, 4505, 4770, 5406, 8109, 9010, 13515, 16218, 27030, 40545, 81090.
What is 81090 in binary?
10011110011000010 (hexadecimal 13CC2, octal 236302).
What is the square root of 81090?
About 284.7631, exactly 3√9010.
Is 81090 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 81090?
81090 is a Harshad number: divisible by its digit sum 18.