The number 28820
28820 is a composite number with 24 divisors. Its prime factorisation is × 5 × 11 × 131. Divisors (24): 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 131, 220, 262, 524, 655 … 28820.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28820: a Harshad number: divisible by its digit sum 20.
- 2
28820 is composite. Its prime factorisation is
- 3
The divisors add up to 66528; without 28820 itself that is 37708, so 28820 is abundant (37708 is more than 28820). Euler's totient φ(28820) = 10400 numbers up to 28820 share no factor with it.
- 4
The digits of 28820 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 165 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28820 = 2^{2} \times 5 \times 11 \times 131 \]28820 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 24 |
| Sum of divisors | 66528 |
| Euler totient φ(n) | 10400 |
| Square | 830592400 |
| Cube | 23937672968000 |
| Square root | 169.764543 (= 2√7205) |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 165 |
| Scientific notation | 2.882 × |
28820 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand eight hundred and twenty |
| Binary (base 2) | 111000010010100 |
| Octal (base 8) | 70224 |
| Hexadecimal (base 16) | 7094 |
| Base 3 | 1110112102 |
| As time | 28820 seconds = 8 h 0 min 20 s |
Is 28820 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (28820 ÷ 2 = 14410) | 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 | Yes (28820 ÷ 4 = 7205) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (28820 ÷ 5 = 5764) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | 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 | No (remainder 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | Yes (28820 ÷ 10 = 2882) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (28820 ÷ 11 = 2620) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28820 a prime number?
No. 28820 = × 5 × 11 × 131, so it is divisible by 2.
What are the factors of 28820?
1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 131, 220, 262, 524, 655, 1310, 1441, 2620, 2882, 5764, 7205, 14410, 28820.
What is 28820 in binary?
111000010010100 (hexadecimal 7094, octal 70224).
What is the square root of 28820?
About 169.7645, exactly 2√7205.
Is 28820 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 28820?
28820 is a Harshad number: divisible by its digit sum 20.