The number 20825
20825 is a composite number with 18 divisors. Its prime factorisation is × × 17. Divisors (18): 1, 5, 7, 17, 25, 35, 49, 85, 119, 175, 245, 425, 595, 833, 1225, 2975 … 20825.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20825: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 17.
- 2
20825 is composite. Its prime factorisation is
- 3
The divisors add up to 31806; without 20825 itself that is 10981, so 20825 is deficient (10981 is less than 20825). Euler's totient φ(20825) = 13440 numbers up to 20825 share no factor with it.
- 4
The digits of 20825 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 149 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20825 = 5^{2} \times 7^{2} \times 17 \]20825 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 18 |
| Sum of divisors | 31806 |
| Euler totient φ(n) | 13440 |
| Square | 433680625 |
| Cube | 9031399015625 |
| Square root | 144.308697 (= 35√17) |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.0825 × |
20825 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand eight hundred and twenty-five |
| Binary (base 2) | 101000101011001 |
| Octal (base 8) | 50531 |
| Hexadecimal (base 16) | 5159 |
| Base 3 | 1001120022 |
| As time | 20825 seconds = 5 h 47 min 5 s |
Is 20825 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 2) | 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 | Yes (20825 ÷ 5 = 4165) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (20825 ÷ 7 = 2975) | 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 8) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | 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 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 20825 a prime number?
No. 20825 = × × 17, so it is divisible by 5.
What are the factors of 20825?
1, 5, 7, 17, 25, 35, 49, 85, 119, 175, 245, 425, 595, 833, 1225, 2975, 4165, 20825.
What is 20825 in binary?
101000101011001 (hexadecimal 5159, octal 50531).
What is the square root of 20825?
About 144.3087, exactly 35√17.
Is 20825 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 20825?
20825 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 17.