The number 28008
28008 is a composite number with 24 divisors. Its prime factorisation is × × 389. Divisors (24): 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72, 389, 778, 1167, 1556 … 28008.
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How to work it out
- 1
What is special about 28008: a Harshad number: divisible by its digit sum 18.
- 2
28008 is composite. Its prime factorisation is
- 3
The divisors add up to 76050; without 28008 itself that is 48042, so 28008 is abundant (48042 is more than 28008). Euler's totient φ(28008) = 9312 numbers up to 28008 share no factor with it.
- 4
The digits of 28008 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 33 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28008 = 2^{3} \times 3^{2} \times 389 \]28008 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 76050 |
| Euler totient φ(n) | 9312 |
| Square | 784448064 |
| Cube | 21970821376512 |
| Square root | 167.355908 (= 6√778) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 33 |
| Scientific notation | 2.8008 × |
28008 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand and eight |
| Binary (base 2) | 110110101101000 |
| Octal (base 8) | 66550 |
| Hexadecimal (base 16) | 6D68 |
| Base 3 | 1102102100 |
| As time | 28008 seconds = 7 h 46 min 48 s |
Is 28008 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (28008 ÷ 2 = 14004) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (28008 ÷ 3 = 9336) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (28008 ÷ 4 = 7002) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | Yes (28008 ÷ 6 = 4668) | 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 | Yes (28008 ÷ 8 = 3501) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (28008 ÷ 9 = 3112) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (28008 ÷ 12 = 2334) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28008 a prime number?
No. 28008 = × × 389, so it is divisible by 2.
What are the factors of 28008?
1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72, 389, 778, 1167, 1556, 2334, 3112, 3501, 4668, 7002, 9336, 14004, 28008.
What is 28008 in binary?
110110101101000 (hexadecimal 6D68, octal 66550).
What is the square root of 28008?
About 167.3559, exactly 6√778.
Is 28008 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 28008?
28008 is a Harshad number: divisible by its digit sum 18.