The number 28231
28231 is a composite number with 8 divisors. Its prime factorisation is 7 × 37 × 109. Divisors (8): 1, 7, 37, 109, 259, 763, 4033, 28231.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28231: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
28231 is composite. Its prime factorisation is
- 3
The divisors add up to 33440; without 28231 itself that is 5209, so 28231 is deficient (5209 is less than 28231). Euler's totient φ(28231) = 23328 numbers up to 28231 share no factor with it.
- 4
The digits of 28231 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 152 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28231 = 7 \times 37 \times 109 \]
28231 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 33440 |
| Euler totient φ(n) | 23328 |
| Square | 796989361 |
| Cube | 22499806650391 |
| Square root | 168.020832 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 152 |
| Scientific notation | 2.8231 × |
28231 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand two hundred and thirty-one |
| Binary (base 2) | 110111001000111 |
| Octal (base 8) | 67107 |
| Hexadecimal (base 16) | 6E47 |
| Base 3 | 1102201121 |
| As time | 28231 seconds = 7 h 50 min 31 s |
Is 28231 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 | No (remainder 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (28231 ÷ 7 = 4033) | 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 | No (remainder 7) | 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 5) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28231 a prime number?
No. 28231 = 7 × 37 × 109, so it is divisible by 7.
What are the factors of 28231?
1, 7, 37, 109, 259, 763, 4033, 28231.
What is 28231 in binary?
110111001000111 (hexadecimal 6E47, octal 67107).
What is the square root of 28231?
About 168.0208.
Is 28231 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 28231?
28231 is a happy number: repeatedly adding the squares of its digits reaches 1.