The number 15731
15731 is a twin prime (15731 and 15733 are both prime) and the 1833rd prime number. Its only divisors are 1 and 15731.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 15731: a twin prime (15731 and 15733 are both prime); the 1833rd prime number.
- 2
15731 is prime, so its only factors are 1 and 15731. It is the 1833rd prime; the next prime is 15733 and the one before is 15727.
- 3
The divisors add up to 15732; without 15731 itself that is 1, so 15731 is deficient (1 is less than 15731). Euler's totient φ(15731) = 15730 numbers up to 15731 share no factor with it.
- 4
The digits of 15731 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 53 steps to reach 1.
15731 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 15732 |
| Euler totient φ(n) | 15730 |
| Square | 247464361 |
| Cube | 3892861862891 |
| Square root | 125.423283 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 53 |
| Scientific notation | 1.5731 × |
15731 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand seven hundred and thirty-one |
| Binary (base 2) | 11110101110011 |
| Octal (base 8) | 36563 |
| Hexadecimal (base 16) | 3D73 |
| Base 3 | 210120122 |
| As time | 15731 seconds = 4 h 22 min 11 s |
Is 15731 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 1) | 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 | 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 3) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 15731 a prime number?
Yes. 15731 is divisible only by 1 and itself.
What are the factors of 15731?
1, 15731.
What is 15731 in binary?
11110101110011 (hexadecimal 3D73, octal 36563).
What is the square root of 15731?
About 125.4233.
Is 15731 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 15731?
15731 is a twin prime (15731 and 15733 are both prime); the 1833rd prime number.