The number 31681
31681 is a composite number with 4 divisors. Its prime factorisation is 13 × 2437. Divisors (4): 1, 13, 2437, 31681.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 31681: a semiprime: 13 × 2437, the product of two primes.
- 2
31681 is composite. Its prime factorisation is
- 3
The divisors add up to 34132; without 31681 itself that is 2451, so 31681 is deficient (2451 is less than 31681). Euler's totient φ(31681) = 29232 numbers up to 31681 share no factor with it.
- 4
The digits of 31681 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 103 steps to reach 1.
LaTeX source of the formulas on this page
\[ 31681 = 13 \times 2437 \]
31681 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 34132 |
| Euler totient φ(n) | 29232 |
| Square | 1003685761 |
| Cube | 31797768594241 |
| Square root | 177.991573 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 103 |
| Scientific notation | 3.1681 × |
31681 in other forms
| Form | Value |
|---|---|
| In words | thirty-one thousand six hundred and eighty-one |
| Binary (base 2) | 111101111000001 |
| Octal (base 8) | 75701 |
| Hexadecimal (base 16) | 7BC1 |
| Base 3 | 1121110101 |
| As time | 31681 seconds = 8 h 48 min 1 s |
Is 31681 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 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 1) | 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 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 31681 a prime number?
No. 31681 = 13 × 2437, so it is divisible by 13.
What are the factors of 31681?
1, 13, 2437, 31681.
What is 31681 in binary?
111101111000001 (hexadecimal 7BC1, octal 75701).
What is the square root of 31681?
About 177.9916.
Is 31681 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 31681?
31681 is a semiprime: 13 × 2437, the product of two primes.