The number 1091
1091 is a twin prime (1091 and 1093 are both prime) and the 182nd prime number. Its only divisors are 1 and 1091.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 1091: a twin prime (1091 and 1093 are both prime); the 182nd prime number.
- 2
1091 is prime, so its only factors are 1 and 1091. It is the 182nd prime; the next prime is 1093 and the one before is 1087.
- 3
The divisors add up to 1092; without 1091 itself that is 1, so 1091 is deficient (1 is less than 1091). Euler's totient φ(1091) = 1090 numbers up to 1091 share no factor with it.
- 4
The digits of 1091 add up to 11, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 44 steps to reach 1.
1091 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 1092 |
| Euler totient φ(n) | 1090 |
| Square | 1190281 |
| Cube | 1298596571 |
| Square root | 33.030289 |
| Digit sum / digital root | 11 / 2 |
| Collatz steps to 1 | 44 |
| Scientific notation | 1.091 × |
1091 in other forms
| Form | Value |
|---|---|
| In words | one thousand and ninety-one |
| Roman numerals | MXCI |
| Binary (base 2) | 10001000011 |
| Octal (base 8) | 2103 |
| Hexadecimal (base 16) | 443 |
| Base 3 | 1111102 |
| As time | 1091 seconds = 18 min 11 s |
Is 1091 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 2) | 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 5) | 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 2) | 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 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 1091 a prime number?
Yes. 1091 is divisible only by 1 and itself.
What are the factors of 1091?
1, 1091.
What is 1091 in binary?
10001000011 (hexadecimal 443, octal 2103).
What is the square root of 1091?
About 33.0303.
What is 1091 in Roman numerals?
MXCI.
Is 1091 divisible by 3?
No. Its digits add up to 11, which is not a multiple of 3.
What is special about the number 1091?
1091 is a twin prime (1091 and 1093 are both prime); the 182nd prime number.