The number 7125
7125 is a composite number with 16 divisors. Its prime factorisation is 3 × × 19. Divisors (16): 1, 3, 5, 15, 19, 25, 57, 75, 95, 125, 285, 375, 475, 1425, 2375, 7125.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 7125: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 15.
- 2
7125 is composite. Its prime factorisation is
- 3
The divisors add up to 12480; without 7125 itself that is 5355, so 7125 is deficient (5355 is less than 7125). Euler's totient φ(7125) = 3600 numbers up to 7125 share no factor with it.
- 4
The digits of 7125 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 75 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7125 = 3 \times 5^{3} \times 19 \]7125 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 12480 |
| Euler totient φ(n) | 3600 |
| Square | 50765625 |
| Cube | 361705078125 |
| Square root | 84.409715 (= 5√285) |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 75 |
| Scientific notation | 7.125 × |
7125 in other forms
| Form | Value |
|---|---|
| In words | seven thousand one hundred and twenty-five |
| Binary (base 2) | 1101111010101 |
| Octal (base 8) | 15725 |
| Hexadecimal (base 16) | 1BD5 |
| Base 3 | 100202220 |
| As time | 7125 seconds = 1 h 58 min 45 s |
Is 7125 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 | Yes (7125 ÷ 3 = 2375) | 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 (7125 ÷ 5 = 1425) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | 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 8) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 7125 a prime number?
No. 7125 = 3 × × 19, so it is divisible by 3.
What are the factors of 7125?
1, 3, 5, 15, 19, 25, 57, 75, 95, 125, 285, 375, 475, 1425, 2375, 7125.
What is 7125 in binary?
1101111010101 (hexadecimal 1BD5, octal 15725).
What is the square root of 7125?
About 84.4097, exactly 5√285.
Is 7125 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 7125?
7125 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 15.