The number 81423
81423 is a composite number with 12 divisors. Its prime factorisation is × 83 × 109. Divisors (12): 1, 3, 9, 83, 109, 249, 327, 747, 981, 9047, 27141, 81423.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81423: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
81423 is composite. Its prime factorisation is
- 3
The divisors add up to 120120; without 81423 itself that is 38697, so 81423 is deficient (38697 is less than 81423). Euler's totient φ(81423) = 53136 numbers up to 81423 share no factor with it.
- 4
The digits of 81423 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 138 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81423 = 3^{2} \times 83 \times 109 \]81423 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 120120 |
| Euler totient φ(n) | 53136 |
| Square | 6629704929 |
| Cube | 539810464433967 |
| Square root | 285.347157 (= 3√9047) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 138 |
| Scientific notation | 8.1423 × |
81423 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand four hundred and twenty-three |
| Binary (base 2) | 10011111000001111 |
| Octal (base 8) | 237017 |
| Hexadecimal (base 16) | 13E0F |
| Base 3 | 11010200200 |
| As time | 81423 seconds = 22 h 37 min 3 s |
Is 81423 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 (81423 ÷ 3 = 27141) | 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 6) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (81423 ÷ 9 = 9047) | 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 1) | 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 81423 a prime number?
No. 81423 = × 83 × 109, so it is divisible by 3.
What are the factors of 81423?
1, 3, 9, 83, 109, 249, 327, 747, 981, 9047, 27141, 81423.
What is 81423 in binary?
10011111000001111 (hexadecimal 13E0F, octal 237017).
What is the square root of 81423?
About 285.3472, exactly 3√9047.
Is 81423 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 81423?
81423 is a happy number: repeatedly adding the squares of its digits reaches 1.