The number 3931
3931 is a twin prime (3929 and 3931 are both prime) and the 546th prime number. Its only divisors are 1 and 3931.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 3931: a twin prime (3929 and 3931 are both prime); the 546th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
3931 is prime, so its only factors are 1 and 3931. It is the 546th prime; the next prime is 3943 and the one before is 3929.
- 3
The divisors add up to 3932; without 3931 itself that is 1, so 3931 is deficient (1 is less than 3931). Euler's totient φ(3931) = 3930 numbers up to 3931 share no factor with it.
- 4
The digits of 3931 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 82 steps to reach 1.
3931 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 3932 |
| Euler totient φ(n) | 3930 |
| Square | 15452761 |
| Cube | 60744803491 |
| Square root | 62.697687 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 82 |
| Scientific notation | 3.931 × |
3931 in other forms
| Form | Value |
|---|---|
| In words | three thousand nine hundred and thirty-one |
| Roman numerals | MMMCMXXXI |
| Binary (base 2) | 111101011011 |
| Octal (base 8) | 7533 |
| Hexadecimal (base 16) | F5B |
| Base 3 | 12101121 |
| As time | 3931 seconds = 1 h 5 min 31 s |
Is 3931 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 4) | 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 7) | 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 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 3931 a prime number?
Yes. 3931 is divisible only by 1 and itself.
What are the factors of 3931?
1, 3931.
What is 3931 in binary?
111101011011 (hexadecimal F5B, octal 7533).
What is the square root of 3931?
About 62.6977.
What is 3931 in Roman numerals?
MMMCMXXXI.
Is 3931 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 3931?
3931 is a twin prime (3929 and 3931 are both prime); the 546th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.