The number 15625
15625 is a perfect power () and a perfect square (125²). Its prime factorisation is . Divisors (7): 1, 5, 25, 125, 625, 3125, 15625.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 15625: a perfect power (); a perfect square (125²); a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
15625 is composite. Its prime factorisation is
- 3
The divisors add up to 19531; without 15625 itself that is 3906, so 15625 is deficient (3906 is less than 15625). Euler's totient φ(15625) = 12500 numbers up to 15625 share no factor with it.
- 4
The digits of 15625 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 146 steps to reach 1.
LaTeX source of the formulas on this page
\[ 15625 = 5^{6} \]15625 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 7 |
| Sum of divisors | 19531 |
| Euler totient φ(n) | 12500 |
| Square | 244140625 |
| Cube | 3814697265625 |
| Square root | 125 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 146 |
| Scientific notation | 1.5625 × |
| Perfect power |
15625 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand six hundred and twenty-five |
| Binary (base 2) | 11110100001001 |
| Octal (base 8) | 36411 |
| Hexadecimal (base 16) | 3D09 |
| Base 3 | 210102201 |
| As time | 15625 seconds = 4 h 20 min 25 s |
Is 15625 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 (15625 ÷ 5 = 3125) | 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 1) | 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 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 15625 a prime number?
No. 15625 = , so it is divisible by 5.
What are the factors of 15625?
1, 5, 25, 125, 625, 3125, 15625.
What is 15625 in binary?
11110100001001 (hexadecimal 3D09, octal 36411).
What is the square root of 15625?
125, because 125 × 125 = 15625.
Is 15625 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 15625?
15625 is a perfect power (); a perfect square (125²); a happy number: repeatedly adding the squares of its digits reaches 1.