The number 31531
31531 is the 3393rd prime number. Its only divisors are 1 and 31531.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31531: the 3393rd prime number.
- 2
31531 is prime, so its only factors are 1 and 31531. It is the 3393rd prime; the next prime is 31541 and the one before is 31517.
- 3
The divisors add up to 31532; without 31531 itself that is 1, so 31531 is deficient (1 is less than 31531). Euler's totient φ(31531) = 31530 numbers up to 31531 share no factor with it.
- 4
The digits of 31531 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 54 steps to reach 1.
31531 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 31532 |
| Euler totient φ(n) | 31530 |
| Square | 994203961 |
| Cube | 31348245094291 |
| Square root | 177.569705 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 54 |
| Scientific notation | 3.1531 × |
31531 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand five hundred and thirty-one |
| Binary (base 2) | 111101100101011 |
| Octal (base 8) | 75453 |
| Hexadecimal (base 16) | 7B2B |
| Base 3 | 1121020211 |
| As time | 31531 seconds = 8 h 45 min 31 s |
Is 31531 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 1) | 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 3) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 5) | 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 31531 a prime number?
Yes. 31531 is divisible only by 1 and itself.
What are the factors of 31531?
1, 31531.
What is 31531 in binary?
111101100101011 (hexadecimal 7B2B, octal 75453).
What is the square root of 31531?
About 177.5697.
Is 31531 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 31531?
31531 is the 3393rd prime number.