The number 20425
20425 is a composite number with 12 divisors. Its prime factorisation is × 19 × 43. Divisors (12): 1, 5, 19, 25, 43, 95, 215, 475, 817, 1075, 4085, 20425.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 20425: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
20425 is composite. Its prime factorisation is
- 3
The divisors add up to 27280; without 20425 itself that is 6855, so 20425 is deficient (6855 is less than 20425). Euler's totient φ(20425) = 15120 numbers up to 20425 share no factor with it.
- 4
The digits of 20425 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 180 steps to reach 1.
LaTeX source of the formulas on this page
\[ 20425 = 5^{2} \times 19 \times 43 \]20425 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 27280 |
| Euler totient φ(n) | 15120 |
| Square | 417180625 |
| Cube | 8520914265625 |
| Square root | 142.916059 (= 5√817) |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 180 |
| Scientific notation | 2.0425 × |
20425 in other forms
| Form | Value |
|---|---|
| In words | twenty thousand four hundred and twenty-five |
| Binary (base 2) | 100111111001001 |
| Octal (base 8) | 47711 |
| Hexadecimal (base 16) | 4FC9 |
| Base 3 | 1001000111 |
| As time | 20425 seconds = 5 h 40 min 25 s |
Is 20425 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 | Yes (20425 ÷ 5 = 4085) | 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 6) | 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 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | 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 20425 a prime number?
No. 20425 = × 19 × 43, so it is divisible by 5.
What are the factors of 20425?
1, 5, 19, 25, 43, 95, 215, 475, 817, 1075, 4085, 20425.
What is 20425 in binary?
100111111001001 (hexadecimal 4FC9, octal 47711).
What is the square root of 20425?
About 142.9161, exactly 5√817.
Is 20425 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 20425?
20425 is a happy number: repeatedly adding the squares of its digits reaches 1.