The number 831
831 is a composite number with 4 divisors. Its prime factorisation is 3 × 277. Divisors (4): 1, 3, 277, 831.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 831: a semiprime: 3 × 277, the product of two primes.
- 2
831 is composite. Its prime factorisation is
- 3
The divisors add up to 1112; without 831 itself that is 281, so 831 is deficient (281 is less than 831). Euler's totient φ(831) = 552 numbers up to 831 share no factor with it.
- 4
The digits of 831 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 134 steps to reach 1.
LaTeX source of the formulas on this page
\[ 831 = 3 \times 277 \]
831 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 1112 |
| Euler totient φ(n) | 552 |
| Square | 690561 |
| Cube | 573856191 |
| Square root | 28.827071 |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 134 |
| Scientific notation | 8.31 × |
831 in other forms
| Form | Value |
|---|---|
| In words | eight hundred and thirty-one |
| Roman numerals | DCCCXXXI |
| Binary (base 2) | 1100111111 |
| Octal (base 8) | 1477 |
| Hexadecimal (base 16) | 33F |
| Base 3 | 1010210 |
| As time | 831 seconds = 13 min 51 s |
Is 831 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 (831 ÷ 3 = 277) | 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 | No (remainder 1) | 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 5) | 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 | No (remainder 3) | 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 6) | 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 831 a prime number?
No. 831 = 3 × 277, so it is divisible by 3.
What are the factors of 831?
1, 3, 277, 831.
What is 831 in binary?
1100111111 (hexadecimal 33F, octal 1477).
What is the square root of 831?
About 28.8271.
What is 831 in Roman numerals?
DCCCXXXI.
Is 831 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 831?
831 is a semiprime: 3 × 277, the product of two primes.