The number 31387
31387 is the 3382nd prime number. Its only divisors are 1 and 31387.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31387: the 3382nd prime number.
- 2
31387 is prime, so its only factors are 1 and 31387. It is the 3382nd prime; the next prime is 31391 and the one before is 31379.
- 3
The divisors add up to 31388; without 31387 itself that is 1, so 31387 is deficient (1 is less than 31387). Euler's totient φ(31387) = 31386 numbers up to 31387 share no factor with it.
- 4
The digits of 31387 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 253 steps to reach 1.
31387 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 31388 |
| Euler totient φ(n) | 31386 |
| Square | 985143769 |
| Cube | 30920707477603 |
| Square root | 177.163766 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 253 |
| Scientific notation | 3.1387 × |
31387 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand three hundred and eighty-seven |
| Binary (base 2) | 111101010011011 |
| Octal (base 8) | 75233 |
| Hexadecimal (base 16) | 7A9B |
| Base 3 | 1121001111 |
| As time | 31387 seconds = 8 h 43 min 7 s |
Is 31387 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 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | 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 4) | 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 31387 a prime number?
Yes. 31387 is divisible only by 1 and itself.
What are the factors of 31387?
1, 31387.
What is 31387 in binary?
111101010011011 (hexadecimal 7A9B, octal 75233).
What is the square root of 31387?
About 177.1638.
Is 31387 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 31387?
31387 is the 3382nd prime number.