The number 81189
81189 is a composite number with 16 divisors. Its prime factorisation is × 31 × 97. Divisors (16): 1, 3, 9, 27, 31, 93, 97, 279, 291, 837, 873, 2619, 3007, 9021, 27063, 81189.
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How to work it out
- 1
What is special about 81189: a Harshad number: divisible by its digit sum 27.
- 2
81189 is composite. Its prime factorisation is
- 3
The divisors add up to 125440; without 81189 itself that is 44251, so 81189 is deficient (44251 is less than 81189). Euler's totient φ(81189) = 51840 numbers up to 81189 share no factor with it.
- 4
The digits of 81189 add up to 27, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 138 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81189 = 3^{3} \times 31 \times 97 \]81189 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 125440 |
| Euler totient φ(n) | 51840 |
| Square | 6591653721 |
| Cube | 535169773954269 |
| Square root | 284.936835 (= 3√9021) |
| Digit sum / digital root | 27 / 9 |
| Collatz steps to 1 | 138 |
| Scientific notation | 8.1189 × |
81189 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand one hundred and eighty-nine |
| Binary (base 2) | 10011110100100101 |
| Octal (base 8) | 236445 |
| Hexadecimal (base 16) | 13D25 |
| Base 3 | 11010101000 |
| As time | 81189 seconds = 22 h 33 min 9 s |
Is 81189 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (81189 ÷ 3 = 27063) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 3) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (81189 ÷ 9 = 9021) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81189 a prime number?
No. 81189 = × 31 × 97, so it is divisible by 3.
What are the factors of 81189?
1, 3, 9, 27, 31, 93, 97, 279, 291, 837, 873, 2619, 3007, 9021, 27063, 81189.
What is 81189 in binary?
10011110100100101 (hexadecimal 13D25, octal 236445).
What is the square root of 81189?
About 284.9368, exactly 3√9021.
Is 81189 divisible by 3?
Yes. Its digits add up to 27, a multiple of 3.
What is special about the number 81189?
81189 is a Harshad number: divisible by its digit sum 27.