The number 31397
31397 is the 3385th prime number. Its only divisors are 1 and 31397.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31397: the 3385th prime number.
- 2
31397 is prime, so its only factors are 1 and 31397. It is the 3385th prime; the next prime is 31469 and the one before is 31393.
- 3
The divisors add up to 31398; without 31397 itself that is 1, so 31397 is deficient (1 is less than 31397). Euler's totient φ(31397) = 31396 numbers up to 31397 share no factor with it.
- 4
The digits of 31397 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 129 steps to reach 1.
31397 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 31398 |
| Euler totient φ(n) | 31396 |
| Square | 985771609 |
| Cube | 30950271207773 |
| Square root | 177.191986 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 129 |
| Scientific notation | 3.1397 × |
31397 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand three hundred and ninety-seven |
| Binary (base 2) | 111101010100101 |
| Octal (base 8) | 75245 |
| Hexadecimal (base 16) | 7AA5 |
| Base 3 | 1121001212 |
| As time | 31397 seconds = 8 h 43 min 17 s |
Is 31397 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 1) | 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 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31397 a prime number?
Yes. 31397 is divisible only by 1 and itself.
What are the factors of 31397?
1, 31397.
What is 31397 in binary?
111101010100101 (hexadecimal 7AA5, octal 75245).
What is the square root of 31397?
About 177.1920.
Is 31397 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 31397?
31397 is the 3385th prime number.