The number 28007
28007 is a composite number with 4 divisors. Its prime factorisation is 7 × 4001. Divisors (4): 1, 7, 4001, 28007.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28007: a semiprime: 7 × 4001, the product of two primes.
- 2
28007 is composite. Its prime factorisation is
- 3
The divisors add up to 32016; without 28007 itself that is 4009, so 28007 is deficient (4009 is less than 28007). Euler's totient φ(28007) = 24000 numbers up to 28007 share no factor with it.
- 4
The digits of 28007 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 183 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28007 = 7 \times 4001 \]
28007 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 32016 |
| Euler totient φ(n) | 24000 |
| Square | 784392049 |
| Cube | 21968468116343 |
| Square root | 167.352921 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 183 |
| Scientific notation | 2.8007 × |
28007 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand and seven |
| Binary (base 2) | 110110101100111 |
| Octal (base 8) | 66547 |
| Hexadecimal (base 16) | 6D67 |
| Base 3 | 1102102022 |
| As time | 28007 seconds = 7 h 46 min 47 s |
Is 28007 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | 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 | Yes (28007 ÷ 7 = 4001) | 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 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 7) | 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 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28007 a prime number?
No. 28007 = 7 × 4001, so it is divisible by 7.
What are the factors of 28007?
1, 7, 4001, 28007.
What is 28007 in binary?
110110101100111 (hexadecimal 6D67, octal 66547).
What is the square root of 28007?
About 167.3529.
Is 28007 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 28007?
28007 is a semiprime: 7 × 4001, the product of two primes.