The number 28431
28431 is a composite number with 16 divisors. Its prime factorisation is × 13. Divisors (16): 1, 3, 9, 13, 27, 39, 81, 117, 243, 351, 729, 1053, 2187, 3159, 9477, 28431.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28431: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
28431 is composite. Its prime factorisation is
- 3
The divisors add up to 45920; without 28431 itself that is 17489, so 28431 is deficient (17489 is less than 28431). Euler's totient φ(28431) = 17496 numbers up to 28431 share no factor with it.
- 4
The digits of 28431 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 59 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28431 = 3^{7} \times 13 \]28431 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 45920 |
| Euler totient φ(n) | 17496 |
| Square | 808321761 |
| Cube | 22981395986991 |
| Square root | 168.614946 (= 27√39) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 59 |
| Scientific notation | 2.8431 × |
28431 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand four hundred and thirty-one |
| Binary (base 2) | 110111100001111 |
| Octal (base 8) | 67417 |
| Hexadecimal (base 16) | 6F0F |
| Base 3 | 1110000000 |
| As time | 28431 seconds = 7 h 53 min 51 s |
Is 28431 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 (28431 ÷ 3 = 9477) | 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 1) | 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 4) | 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 (28431 ÷ 9 = 3159) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | 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 28431 a prime number?
No. 28431 = × 13, so it is divisible by 3.
What are the factors of 28431?
1, 3, 9, 13, 27, 39, 81, 117, 243, 351, 729, 1053, 2187, 3159, 9477, 28431.
What is 28431 in binary?
110111100001111 (hexadecimal 6F0F, octal 67417).
What is the square root of 28431?
About 168.6149, exactly 27√39.
Is 28431 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 28431?
28431 is a happy number: repeatedly adding the squares of its digits reaches 1.