The number 21625
21625 is a composite number with 8 divisors. Its prime factorisation is Ć 173. Divisors (8): 1, 5, 25, 125, 173, 865, 4325, 21625.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21625: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21625 is composite. Its prime factorisation is
- 3
The divisors add up to 27144; without 21625 itself that is 5519, so 21625 is deficient (5519 is less than 21625). Euler's totient Ļ(21625) = 17200 numbers up to 21625 share no factor with it.
- 4
The digits of 21625 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 193 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21625 = 5^{3} \times 173 \]21625 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 27144 |
| Euler totient Ļ(n) | 17200 |
| Square | 467640625 |
| Cube | 10112728515625 |
| Square root | 147.054412 (= 5ā865) |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.1625 Ć |
21625 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand six hundred and twenty-five |
| Binary (base 2) | 101010001111001 |
| Octal (base 8) | 52171 |
| Hexadecimal (base 16) | 5479 |
| Base 3 | 1002122221 |
| As time | 21625 seconds = 6 h 0 min 25 s |
Is 21625 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 (21625 Ć· 5 = 4325) | 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 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 | No (remainder 1) | 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 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | 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 21625 a prime number?
No. 21625 = Ć 173, so it is divisible by 5.
What are the factors of 21625?
1, 5, 25, 125, 173, 865, 4325, 21625.
What is 21625 in binary?
101010001111001 (hexadecimal 5479, octal 52171).
What is the square root of 21625?
About 147.0544, exactly 5ā865.
Is 21625 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 21625?
21625 is a happy number: repeatedly adding the squares of its digits reaches 1.