The number 42791
42791 is a composite number with 4 divisors. Its prime factorisation is 7 × 6113. Divisors (4): 1, 7, 6113, 42791.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42791: a semiprime: 7 × 6113, the product of two primes.
- 2
42791 is composite. Its prime factorisation is
- 3
The divisors add up to 48912; without 42791 itself that is 6121, so 42791 is deficient (6121 is less than 42791). Euler's totient φ(42791) = 36672 numbers up to 42791 share no factor with it.
- 4
The digits of 42791 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 163 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42791 = 7 \times 6113 \]
42791 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 48912 |
| Euler totient φ(n) | 36672 |
| Square | 1831069681 |
| Cube | 78353302719671 |
| Square root | 206.859856 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 163 |
| Scientific notation | 4.2791 × |
42791 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand seven hundred and ninety-one |
| Binary (base 2) | 1010011100100111 |
| Octal (base 8) | 123447 |
| Hexadecimal (base 16) | A727 |
| Base 3 | 2011200212 |
| As time | 42791 seconds = 11 h 53 min 11 s |
Is 42791 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 (42791 ÷ 7 = 6113) | 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 5) | 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 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 42791 a prime number?
No. 42791 = 7 × 6113, so it is divisible by 7.
What are the factors of 42791?
1, 7, 6113, 42791.
What is 42791 in binary?
1010011100100111 (hexadecimal A727, octal 123447).
What is the square root of 42791?
About 206.8599.
Is 42791 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 42791?
42791 is a semiprime: 7 × 6113, the product of two primes.