The number 31687
31687 is the 3408th prime number. Its only divisors are 1 and 31687.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31687: the 3408th prime number.
- 2
31687 is prime, so its only factors are 1 and 31687. It is the 3408th prime; the next prime is 31699 and the one before is 31667.
- 3
The divisors add up to 31688; without 31687 itself that is 1, so 31687 is deficient (1 is less than 31687). Euler's totient φ(31687) = 31686 numbers up to 31687 share no factor with it.
- 4
The digits of 31687 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 284 steps to reach 1.
31687 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 31688 |
| Euler totient φ(n) | 31686 |
| Square | 1004065969 |
| Cube | 31815838359703 |
| Square root | 178.008427 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 284 |
| Scientific notation | 3.1687 × |
31687 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand six hundred and eighty-seven |
| Binary (base 2) | 111101111000111 |
| Octal (base 8) | 75707 |
| Hexadecimal (base 16) | 7BC7 |
| Base 3 | 1121110121 |
| As time | 31687 seconds = 8 h 48 min 7 s |
Is 31687 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | 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 5) | 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 7) | 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 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31687 a prime number?
Yes. 31687 is divisible only by 1 and itself.
What are the factors of 31687?
1, 31687.
What is 31687 in binary?
111101111000111 (hexadecimal 7BC7, octal 75707).
What is the square root of 31687?
About 178.0084.
Is 31687 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 31687?
31687 is the 3408th prime number.