The number 8081
8081 is the 1015th prime number. Its only divisors are 1 and 8081.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 8081: the 1015th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
8081 is prime, so its only factors are 1 and 8081. It is the 1015th prime; the next prime is 8087 and the one before is 8069.
- 3
The divisors add up to 8082; without 8081 itself that is 1, so 8081 is deficient (1 is less than 8081). Euler's totient φ(8081) = 8080 numbers up to 8081 share no factor with it.
- 4
The digits of 8081 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 145 steps to reach 1.
8081 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 8082 |
| Euler totient φ(n) | 8080 |
| Square | 65302561 |
| Cube | 527709995441 |
| Square root | 89.894382 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 145 |
| Scientific notation | 8.081 × |
8081 in other forms
| Form | Value |
|---|---|
| In words | eight thousand and eighty-one |
| Binary (base 2) | 1111110010001 |
| Octal (base 8) | 17621 |
| Hexadecimal (base 16) | 1F91 |
| Base 3 | 102002022 |
| As time | 8081 seconds = 2 h 14 min 41 s |
Is 8081 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 1) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 8) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 8081 a prime number?
Yes. 8081 is divisible only by 1 and itself.
What are the factors of 8081?
1, 8081.
What is 8081 in binary?
1111110010001 (hexadecimal 1F91, octal 17621).
What is the square root of 8081?
About 89.8944.
Is 8081 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 8081?
8081 is the 1015th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.