The number 81489
81489 is a composite number with 8 divisors. Its prime factorisation is 3 × 23 × 1181. Divisors (8): 1, 3, 23, 69, 1181, 3543, 27163, 81489.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81489: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81489 is composite. Its prime factorisation is
- 3
The divisors add up to 113472; without 81489 itself that is 31983, so 81489 is deficient (31983 is less than 81489). Euler's totient φ(81489) = 51920 numbers up to 81489 share no factor with it.
- 4
The digits of 81489 add up to 30, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 37 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81489 = 3 \times 23 \times 1181 \]
81489 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 113472 |
| Euler totient φ(n) | 51920 |
| Square | 6640457121 |
| Cube | 541124210333169 |
| Square root | 285.462782 |
| Digit sum / digital root | 30 / 3 |
| Collatz steps to 1 | 37 |
| Scientific notation | 8.1489 × |
81489 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand four hundred and eighty-nine |
| Binary (base 2) | 10011111001010001 |
| Octal (base 8) | 237121 |
| Hexadecimal (base 16) | 13E51 |
| Base 3 | 11010210010 |
| As time | 81489 seconds = 22 h 38 min 9 s |
Is 81489 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 (81489 ÷ 3 = 27163) | 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 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 1) | 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 81489 a prime number?
No. 81489 = 3 × 23 × 1181, so it is divisible by 3.
What are the factors of 81489?
1, 3, 23, 69, 1181, 3543, 27163, 81489.
What is 81489 in binary?
10011111001010001 (hexadecimal 13E51, octal 237121).
What is the square root of 81489?
About 285.4628.
Is 81489 divisible by 3?
Yes. Its digits add up to 30, a multiple of 3.
What is special about the number 81489?
81489 is a happy number: repeatedly adding the squares of its digits reaches 1.