The number 855
855 is a composite number with 12 divisors. Its prime factorisation is × 5 × 19. Divisors (12): 1, 3, 5, 9, 15, 19, 45, 57, 95, 171, 285, 855.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
855 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
855 is composite. Its prime factorisation is
- 3
The divisors add up to 1560; without 855 itself that is 705, so 855 is deficient (705 is less than 855). Euler's totient φ(855) = 432 numbers up to 855 share no factor with it.
- 4
The digits of 855 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 54 steps to reach 1.
LaTeX source of the formulas on this page
\[ 855 = 3^{2} \times 5 \times 19 \]855 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 1560 |
| Euler totient φ(n) | 432 |
| Square | 731025 |
| Cube | 625026375 |
| Square root | 29.240383 (= 3√95) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 54 |
| Scientific notation | 8.55 × |
855 in other forms
| Form | Value |
|---|---|
| In words | eight hundred and fifty-five |
| Roman numerals | DCCCLV |
| Binary (base 2) | 1101010111 |
| Octal (base 8) | 1527 |
| Hexadecimal (base 16) | 357 |
| Base 3 | 1011200 |
| As time | 855 seconds = 14 min 15 s |
Is 855 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 | Yes (855 ÷ 3 = 285) | 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 | Yes (855 ÷ 5 = 171) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 | No (remainder 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (855 ÷ 9 = 95) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 855 a prime number?
No. 855 = × 5 × 19, so it is divisible by 3.
What are the factors of 855?
1, 3, 5, 9, 15, 19, 45, 57, 95, 171, 285, 855.
What is 855 in binary?
1101010111 (hexadecimal 357, octal 1527).
What is the square root of 855?
About 29.2404, exactly 3√95.
What is 855 in Roman numerals?
DCCCLV.
Is 855 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 855?
It is a composite number with 12 divisors.