The number 2731
2731 is a twin prime (2729 and 2731 are both prime) and the 399th prime number. Its only divisors are 1 and 2731.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 2731: a twin prime (2729 and 2731 are both prime); the 399th prime number.
- 2
2731 is prime, so its only factors are 1 and 2731. It is the 399th prime; the next prime is 2741 and the one before is 2729.
- 3
The divisors add up to 2732; without 2731 itself that is 1, so 2731 is deficient (1 is less than 2731). Euler's totient φ(2731) = 2730 numbers up to 2731 share no factor with it.
- 4
The digits of 2731 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 115 steps to reach 1.
2731 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 2732 |
| Euler totient φ(n) | 2730 |
| Square | 7458361 |
| Cube | 20368783891 |
| Square root | 52.258971 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 115 |
| Scientific notation | 2.731 × |
2731 in other forms
| Form | Value |
|---|---|
| In words | two thousand seven hundred and thirty-one |
| Roman numerals | MMDCCXXXI |
| Binary (base 2) | 101010101011 |
| Octal (base 8) | 5253 |
| Hexadecimal (base 16) | AAB |
| Base 3 | 10202011 |
| As time | 2731 seconds = 45 min 31 s |
Is 2731 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 1) | 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 3) | 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 2731 a prime number?
Yes. 2731 is divisible only by 1 and itself.
What are the factors of 2731?
1, 2731.
What is 2731 in binary?
101010101011 (hexadecimal AAB, octal 5253).
What is the square root of 2731?
About 52.2590.
What is 2731 in Roman numerals?
MMDCCXXXI.
Is 2731 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 2731?
2731 is a twin prime (2729 and 2731 are both prime); the 399th prime number.