The number 4091
4091 is a twin prime (4091 and 4093 are both prime) and the 563rd prime number. Its only divisors are 1 and 4091.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 4091: a twin prime (4091 and 4093 are both prime); the 563rd prime number.
- 2
4091 is prime, so its only factors are 1 and 4091. It is the 563rd prime; the next prime is 4093 and the one before is 4079.
- 3
The divisors add up to 4092; without 4091 itself that is 1, so 4091 is deficient (1 is less than 4091). Euler's totient φ(4091) = 4090 numbers up to 4091 share no factor with it.
- 4
The digits of 4091 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 126 steps to reach 1.
4091 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 4092 |
| Euler totient φ(n) | 4090 |
| Square | 16736281 |
| Cube | 68468125571 |
| Square root | 63.960926 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 126 |
| Scientific notation | 4.091 × |
4091 in other forms
| Form | Value |
|---|---|
| In words | four thousand and ninety-one |
| Binary (base 2) | 111111111011 |
| Octal (base 8) | 7773 |
| Hexadecimal (base 16) | FFB |
| Base 3 | 12121112 |
| As time | 4091 seconds = 1 h 8 min 11 s |
Is 4091 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 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 5) | 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 10) | 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 4091 a prime number?
Yes. 4091 is divisible only by 1 and itself.
What are the factors of 4091?
1, 4091.
What is 4091 in binary?
111111111011 (hexadecimal FFB, octal 7773).
What is the square root of 4091?
About 63.9609.
Is 4091 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 4091?
4091 is a twin prime (4091 and 4093 are both prime); the 563rd prime number.