The number 31999
31999 is a composite number with 4 divisors. Its prime factorisation is 11 × 2909. Divisors (4): 1, 11, 2909, 31999.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31999: a semiprime: 11 × 2909, the product of two primes.
- 2
31999 is composite. Its prime factorisation is
- 3
The divisors add up to 34920; without 31999 itself that is 2921, so 31999 is deficient (2921 is less than 31999). Euler's totient φ(31999) = 29080 numbers up to 31999 share no factor with it.
- 4
The digits of 31999 add up to 31, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 98 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31999 = 11 \times 2909 \]
31999 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 34920 |
| Euler totient φ(n) | 29080 |
| Square | 1023936001 |
| Cube | 32764928095999 |
| Square root | 178.882643 |
| Digit sum / digital root | 31 / 4 |
| Collatz steps to 1 | 98 |
| Scientific notation | 3.1999 × |
31999 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand nine hundred and ninety-nine |
| Binary (base 2) | 111110011111111 |
| Octal (base 8) | 76377 |
| Hexadecimal (base 16) | 7CFF |
| Base 3 | 1121220011 |
| As time | 31999 seconds = 8 h 53 min 19 s |
Is 31999 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 1) | 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 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 1) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 9) | A number is divisible by 10 if the last digit is 0. |
| 11 | Yes (31999 ÷ 11 = 2909) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31999 a prime number?
No. 31999 = 11 × 2909, so it is divisible by 11.
What are the factors of 31999?
1, 11, 2909, 31999.
What is 31999 in binary?
111110011111111 (hexadecimal 7CFF, octal 76377).
What is the square root of 31999?
About 178.8826.
Is 31999 divisible by 3?
No. Its digits add up to 31, which is not a multiple of 3.
What is special about the number 31999?
31999 is a semiprime: 11 × 2909, the product of two primes.