The number 2791
2791 is a twin prime (2789 and 2791 are both prime) and the 406th prime number. Its only divisors are 1 and 2791.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 2791: a twin prime (2789 and 2791 are both prime); the 406th prime number.
- 2
2791 is prime, so its only factors are 1 and 2791. It is the 406th prime; the next prime is 2797 and the one before is 2789.
- 3
The divisors add up to 2792; without 2791 itself that is 1, so 2791 is deficient (1 is less than 2791). Euler's totient φ(2791) = 2790 numbers up to 2791 share no factor with it.
- 4
The digits of 2791 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 66 steps to reach 1.
2791 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 2792 |
| Euler totient φ(n) | 2790 |
| Square | 7789681 |
| Cube | 21740999671 |
| Square root | 52.829916 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 66 |
| Scientific notation | 2.791 × |
2791 in other forms
| Form | Value |
|---|---|
| In words | two thousand seven hundred and ninety-one |
| Roman numerals | MMDCCXCI |
| Binary (base 2) | 101011100111 |
| Octal (base 8) | 5347 |
| Hexadecimal (base 16) | AE7 |
| Base 3 | 10211101 |
| As time | 2791 seconds = 46 min 31 s |
Is 2791 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 5) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | 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 8) | 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 2791 a prime number?
Yes. 2791 is divisible only by 1 and itself.
What are the factors of 2791?
1, 2791.
What is 2791 in binary?
101011100111 (hexadecimal AE7, octal 5347).
What is the square root of 2791?
About 52.8299.
What is 2791 in Roman numerals?
MMDCCXCI.
Is 2791 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 2791?
2791 is a twin prime (2789 and 2791 are both prime); the 406th prime number.