The number 28561
28561 is a perfect power () and a perfect square (169²). Its prime factorisation is . Divisors (5): 1, 13, 169, 2197, 28561.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 28561: a perfect power (); a perfect square (169²); a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
28561 is composite. Its prime factorisation is
- 3
The divisors add up to 30941; without 28561 itself that is 2380, so 28561 is deficient (2380 is less than 28561). Euler's totient φ(28561) = 26364 numbers up to 28561 share no factor with it.
- 4
The digits of 28561 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 103 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28561 = 13^{4} \]28561 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 5 |
| Sum of divisors | 30941 |
| Euler totient φ(n) | 26364 |
| Square | 815730721 |
| Cube | 23298085122481 |
| Square root | 169 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 103 |
| Scientific notation | 2.8561 × |
| Perfect power |
28561 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand five hundred and sixty-one |
| Binary (base 2) | 110111110010001 |
| Octal (base 8) | 67621 |
| Hexadecimal (base 16) | 6F91 |
| Base 3 | 1110011211 |
| As time | 28561 seconds = 7 h 56 min 1 s |
Is 28561 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 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | 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 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 28561 a prime number?
No. 28561 = , so it is divisible by 13.
What are the factors of 28561?
1, 13, 169, 2197, 28561.
What is 28561 in binary?
110111110010001 (hexadecimal 6F91, octal 67621).
What is the square root of 28561?
169, because 169 × 169 = 28561.
Is 28561 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 28561?
28561 is a perfect power (); a perfect square (169²); a happy number: repeatedly adding the squares of its digits reaches 1.