The number 28000
28000 is a composite number with 48 divisors. Its prime factorisation is × × 7. Divisors (48): 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 25, 28, 32, 35, 40, 50 … 28000.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28000: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 10.
- 2
28000 is composite. Its prime factorisation is
- 3
The divisors add up to 78624; without 28000 itself that is 50624, so 28000 is abundant (50624 is more than 28000). Euler's totient φ(28000) = 9600 numbers up to 28000 share no factor with it.
- 4
The digits of 28000 add up to 10, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 33 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28000 = 2^{5} \times 5^{3} \times 7 \]28000 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 48 |
| Sum of divisors | 78624 |
| Euler totient φ(n) | 9600 |
| Square | 784000000 |
| Cube | 21952000000000 |
| Square root | 167.332005 (= 20√70) |
| Digit sum / digital root | 10 / 1 |
| Collatz steps to 1 | 33 |
| Scientific notation | 2.8 × |
28000 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand |
| Binary (base 2) | 110110101100000 |
| Octal (base 8) | 66540 |
| Hexadecimal (base 16) | 6D60 |
| Base 3 | 1102102001 |
| As time | 28000 seconds = 7 h 46 min 40 s |
Is 28000 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (28000 ÷ 2 = 14000) | 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 | Yes (28000 ÷ 4 = 7000) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (28000 ÷ 5 = 5600) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (28000 ÷ 7 = 4000) | 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 (28000 ÷ 8 = 3500) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (28000 ÷ 10 = 2800) | 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 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28000 a prime number?
No. 28000 = × × 7, so it is divisible by 2.
What are the factors of 28000?
1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 25, 28, 32, 35, 40, 50, 56, 70, 80, 100, 112, 125, 140, 160, 175, 200, 224, 250, 280, 350, 400, 500, 560, 700, 800, 875, 1000, 1120, 1400, 1750, 2000, 2800, 3500, 4000, 5600, 7000, 14000, 28000.
What is 28000 in binary?
110110101100000 (hexadecimal 6D60, octal 66540).
What is the square root of 28000?
About 167.3320, exactly 20√70.
Is 28000 divisible by 3?
No. Its digits add up to 10, which is not a multiple of 3.
What is special about the number 28000?
28000 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 10.