The number 28011
28011 is a composite number with 4 divisors. Its prime factorisation is 3 × 9337. Divisors (4): 1, 3, 9337, 28011.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28011: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 9337, the product of two primes.
- 2
28011 is composite. Its prime factorisation is
- 3
The divisors add up to 37352; without 28011 itself that is 9341, so 28011 is deficient (9341 is less than 28011). Euler's totient φ(28011) = 18672 numbers up to 28011 share no factor with it.
- 4
The digits of 28011 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 90 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28011 = 3 \times 9337 \]
28011 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 37352 |
| Euler totient φ(n) | 18672 |
| Square | 784616121 |
| Cube | 21977882165331 |
| Square root | 167.364871 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 90 |
| Scientific notation | 2.8011 × |
28011 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand and eleven |
| Binary (base 2) | 110110101101011 |
| Octal (base 8) | 66553 |
| Hexadecimal (base 16) | 6D6B |
| Base 3 | 1102102110 |
| As time | 28011 seconds = 7 h 46 min 51 s |
Is 28011 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 (28011 ÷ 3 = 9337) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28011 a prime number?
No. 28011 = 3 × 9337, so it is divisible by 3.
What are the factors of 28011?
1, 3, 9337, 28011.
What is 28011 in binary?
110110101101011 (hexadecimal 6D6B, octal 66553).
What is the square root of 28011?
About 167.3649.
Is 28011 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 28011?
28011 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 3 × 9337, the product of two primes.