The number 86
86 is a composite number with 4 divisors. Its prime factorisation is 2 × 43. Divisors (4): 1, 2, 43, 86.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 86: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 43, the product of two primes.
- 2
86 is composite. Its prime factorisation is
- 3
The divisors add up to 132; without 86 itself that is 46, so 86 is deficient (46 is less than 86). Euler's totient φ(86) = 42 numbers up to 86 share no factor with it.
- 4
The digits of 86 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 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 86 = 2 \times 43 \]
86 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 132 |
| Euler totient φ(n) | 42 |
| Square | 7396 |
| Cube | 636056 |
| Square root | 9.273618 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 30 |
| Scientific notation | 8.6 × |
86 in other forms
| Form | Value |
|---|---|
| In words | eighty-six |
| Roman numerals | LXXXVI |
| Binary (base 2) | 1010110 |
| Octal (base 8) | 126 |
| Hexadecimal (base 16) | 56 |
| Base 3 | 10012 |
| As time | 86 seconds = 1 min 26 s |
Is 86 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (86 ÷ 2 = 43) | 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 2) | 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 2) | 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 6) | 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 6) | 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 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 86 a prime number?
No. 86 = 2 × 43, so it is divisible by 2.
What are the factors of 86?
1, 2, 43, 86.
What is 86 in binary?
1010110 (hexadecimal 56, octal 126).
What is the square root of 86?
About 9.2736.
What is 86 in Roman numerals?
LXXXVI.
Is 86 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 86?
86 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 2 × 43, the product of two primes.