The number 28001
28001 is the 3056th prime number. Its only divisors are 1 and 28001.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28001: the 3056th prime number.
- 2
28001 is prime, so its only factors are 1 and 28001. It is the 3056th prime; the next prime is 28019 and the one before is 27997.
- 3
The divisors add up to 28002; without 28001 itself that is 1, so 28001 is deficient (1 is less than 28001). Euler's totient φ(28001) = 28000 numbers up to 28001 share no factor with it.
- 4
The digits of 28001 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 152 steps to reach 1.
28001 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 28002 |
| Euler totient φ(n) | 28000 |
| Square | 784056001 |
| Cube | 21954352084001 |
| Square root | 167.334993 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 152 |
| Scientific notation | 2.8001 × |
28001 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand and one |
| Binary (base 2) | 110110101100001 |
| Octal (base 8) | 66541 |
| Hexadecimal (base 16) | 6D61 |
| Base 3 | 1102102002 |
| As time | 28001 seconds = 7 h 46 min 41 s |
Is 28001 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 2) | 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 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | 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 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28001 a prime number?
Yes. 28001 is divisible only by 1 and itself.
What are the factors of 28001?
1, 28001.
What is 28001 in binary?
110110101100001 (hexadecimal 6D61, octal 66541).
What is the square root of 28001?
About 167.3350.
Is 28001 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 28001?
28001 is the 3056th prime number.