The number 81320
81320 is a composite number with 32 divisors. Its prime factorisation is × 5 × 19 × 107. Divisors (32): 1, 2, 4, 5, 8, 10, 19, 20, 38, 40, 76, 95, 107, 152, 190, 214 … 81320.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
81320 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
81320 is composite. Its prime factorisation is
- 3
The divisors add up to 194400; without 81320 itself that is 113080, so 81320 is abundant (113080 is more than 81320). Euler's totient φ(81320) = 30528 numbers up to 81320 share no factor with it.
- 4
The digits of 81320 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 37 steps to reach 1.
LaTeX source of the formulas on this page
\[ 81320 = 2^{3} \times 5 \times 19 \times 107 \]81320 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 32 |
| Sum of divisors | 194400 |
| Euler totient φ(n) | 30528 |
| Square | 6612942400 |
| Cube | 537764475968000 |
| Square root | 285.166618 (= 2√20330) |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 37 |
| Scientific notation | 8.132 × |
81320 in other forms
| Form | Value |
|---|---|
| In words | eighty-one thousand three hundred and twenty |
| Binary (base 2) | 10011110110101000 |
| Octal (base 8) | 236650 |
| Hexadecimal (base 16) | 13DA8 |
| Base 3 | 11010112212 |
| As time | 81320 seconds = 22 h 35 min 20 s |
Is 81320 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (81320 ÷ 2 = 40660) | 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 | Yes (81320 ÷ 4 = 20330) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (81320 ÷ 5 = 16264) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 1) | 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 | Yes (81320 ÷ 8 = 10165) | 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 | Yes (81320 ÷ 10 = 8132) | 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 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 81320 a prime number?
No. 81320 = × 5 × 19 × 107, so it is divisible by 2.
What are the factors of 81320?
1, 2, 4, 5, 8, 10, 19, 20, 38, 40, 76, 95, 107, 152, 190, 214, 380, 428, 535, 760, 856, 1070, 2033, 2140, 4066, 4280, 8132, 10165, 16264, 20330, 40660, 81320.
What is 81320 in binary?
10011110110101000 (hexadecimal 13DA8, octal 236650).
What is the square root of 81320?
About 285.1666, exactly 2√20330.
Is 81320 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 81320?
It is a composite number with 32 divisors.