The number 31871
31871 is a composite number with 8 divisors. Its prime factorisation is 7 × 29 × 157. Divisors (8): 1, 7, 29, 157, 203, 1099, 4553, 31871.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
31871 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
31871 is composite. Its prime factorisation is
- 3
The divisors add up to 37920; without 31871 itself that is 6049, so 31871 is deficient (6049 is less than 31871). Euler's totient φ(31871) = 26208 numbers up to 31871 share no factor with it.
- 4
The digits of 31871 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 147 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31871 = 7 \times 29 \times 157 \]
31871 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 37920 |
| Euler totient φ(n) | 26208 |
| Square | 1015760641 |
| Cube | 32373307389311 |
| Square root | 178.524508 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 147 |
| Scientific notation | 3.1871 × |
31871 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand eight hundred and seventy-one |
| Binary (base 2) | 111110001111111 |
| Octal (base 8) | 76177 |
| Hexadecimal (base 16) | 7C7F |
| Base 3 | 1121201102 |
| As time | 31871 seconds = 8 h 51 min 11 s |
Is 31871 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 2) | 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 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (31871 ÷ 7 = 4553) | 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 2) | 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 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31871 a prime number?
No. 31871 = 7 × 29 × 157, so it is divisible by 7.
What are the factors of 31871?
1, 7, 29, 157, 203, 1099, 4553, 31871.
What is 31871 in binary?
111110001111111 (hexadecimal 7C7F, octal 76177).
What is the square root of 31871?
About 178.5245.
Is 31871 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 31871?
It is a composite number with 8 divisors.