The number 28240
28240 is a composite number with 20 divisors. Its prime factorisation is × 5 × 353. Divisors (20): 1, 2, 4, 5, 8, 10, 16, 20, 40, 80, 353, 706, 1412, 1765, 2824, 3530 … 28240.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28240: a Harshad number: divisible by its digit sum 16.
- 2
28240 is composite. Its prime factorisation is
- 3
The divisors add up to 65844; without 28240 itself that is 37604, so 28240 is abundant (37604 is more than 28240). Euler's totient φ(28240) = 11264 numbers up to 28240 share no factor with it.
- 4
The digits of 28240 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 33 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28240 = 2^{4} \times 5 \times 353 \]28240 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 20 |
| Sum of divisors | 65844 |
| Euler totient φ(n) | 11264 |
| Square | 797497600 |
| Cube | 22521332224000 |
| Square root | 168.047612 (= 4√1765) |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 33 |
| Scientific notation | 2.824 × |
28240 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand two hundred and forty |
| Binary (base 2) | 110111001010000 |
| Octal (base 8) | 67120 |
| Hexadecimal (base 16) | 6E50 |
| Base 3 | 1102201221 |
| As time | 28240 seconds = 7 h 50 min 40 s |
Is 28240 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (28240 ÷ 2 = 14120) | 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 (28240 ÷ 4 = 7060) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (28240 ÷ 5 = 5648) | 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 | No (remainder 2) | 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 (28240 ÷ 8 = 3530) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (28240 ÷ 10 = 2824) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | 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 28240 a prime number?
No. 28240 = × 5 × 353, so it is divisible by 2.
What are the factors of 28240?
1, 2, 4, 5, 8, 10, 16, 20, 40, 80, 353, 706, 1412, 1765, 2824, 3530, 5648, 7060, 14120, 28240.
What is 28240 in binary?
110111001010000 (hexadecimal 6E50, octal 67120).
What is the square root of 28240?
About 168.0476, exactly 4√1765.
Is 28240 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 28240?
28240 is a Harshad number: divisible by its digit sum 16.