The number 81013
81013 is the 7927th prime number. Its only divisors are 1 and 81013.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 81013: the 7927th prime number.
- 2
81013 is prime, so its only factors are 1 and 81013. It is the 7927th prime; the next prime is 81017 and the one before is 81001.
- 3
The divisors add up to 81014; without 81013 itself that is 1, so 81013 is deficient (1 is less than 81013). Euler's totient φ(81013) = 81012 numbers up to 81013 share no factor with it.
- 4
The digits of 81013 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 138 steps to reach 1.
81013 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 81014 |
| Euler totient φ(n) | 81012 |
| Square | 6563106169 |
| Cube | 531696920069197 |
| Square root | 284.627827 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 138 |
| Scientific notation | 8.1013 × |
81013 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand and thirteen |
| Binary (base 2) | 10011110001110101 |
| Octal (base 8) | 236165 |
| Hexadecimal (base 16) | 13C75 |
| Base 3 | 11010010111 |
| As time | 81013 seconds = 22 h 30 min 13 s |
Is 81013 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 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | 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 2) | 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 5) | 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 3) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81013 a prime number?
Yes. 81013 is divisible only by 1 and itself.
What are the factors of 81013?
1, 81013.
What is 81013 in binary?
10011110001110101 (hexadecimal 13C75, octal 236165).
What is the square root of 81013?
About 284.6278.
Is 81013 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 81013?
81013 is the 7927th prime number.