The number 81243
81243 is a composite number with 20 divisors. Its prime factorisation is × 17 × 59. Divisors (20): 1, 3, 9, 17, 27, 51, 59, 81, 153, 177, 459, 531, 1003, 1377, 1593, 3009 … 81243.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81243: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81243 is composite. Its prime factorisation is
- 3
The divisors add up to 130680; without 81243 itself that is 49437, so 81243 is deficient (49437 is less than 81243). Euler's totient φ(81243) = 50112 numbers up to 81243 share no factor with it.
- 4
The digits of 81243 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 182 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81243 = 3^{4} \times 17 \times 59 \]81243 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 130680 |
| Euler totient φ(n) | 50112 |
| Square | 6600425049 |
| Cube | 536238332255907 |
| Square root | 285.031577 (= 9√1003) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 182 |
| Scientific notation | 8.1243 × |
81243 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand two hundred and forty-three |
| Binary (base 2) | 10011110101011011 |
| Octal (base 8) | 236533 |
| Hexadecimal (base 16) | 13D5B |
| Base 3 | 11010110000 |
| As time | 81243 seconds = 22 h 34 min 3 s |
Is 81243 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 (81243 ÷ 3 = 27081) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | 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 1) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (81243 ÷ 9 = 9027) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81243 a prime number?
No. 81243 = × 17 × 59, so it is divisible by 3.
What are the factors of 81243?
1, 3, 9, 17, 27, 51, 59, 81, 153, 177, 459, 531, 1003, 1377, 1593, 3009, 4779, 9027, 27081, 81243.
What is 81243 in binary?
10011110101011011 (hexadecimal 13D5B, octal 236533).
What is the square root of 81243?
About 285.0316, exactly 9√1003.
Is 81243 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 81243?
81243 is a happy number: repeatedly adding the squares of its digits reaches 1.