The number 42991
42991 is a composite number with 4 divisors. Its prime factorisation is 13 × 3307. Divisors (4): 1, 13, 3307, 42991.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42991: a semiprime: 13 × 3307, the product of two primes.
- 2
42991 is composite. Its prime factorisation is
- 3
The divisors add up to 46312; without 42991 itself that is 3321, so 42991 is deficient (3321 is less than 42991). Euler's totient φ(42991) = 39672 numbers up to 42991 share no factor with it.
- 4
The digits of 42991 add up to 25, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 101 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42991 = 13 \times 3307 \]
42991 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 46312 |
| Euler totient φ(n) | 39672 |
| Square | 1848226081 |
| Cube | 79457087448271 |
| Square root | 207.342711 |
| Digit sum / digital root | 25 / 7 |
| Collatz steps to 1 | 101 |
| Scientific notation | 4.2991 × |
42991 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand nine hundred and ninety-one |
| Binary (base 2) | 1010011111101111 |
| Octal (base 8) | 123757 |
| Hexadecimal (base 16) | A7EF |
| Base 3 | 2011222021 |
| As time | 42991 seconds = 11 h 56 min 31 s |
Is 42991 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 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 4) | 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 7) | 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 3) | 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 42991 a prime number?
No. 42991 = 13 × 3307, so it is divisible by 13.
What are the factors of 42991?
1, 13, 3307, 42991.
What is 42991 in binary?
1010011111101111 (hexadecimal A7EF, octal 123757).
What is the square root of 42991?
About 207.3427.
Is 42991 divisible by 3?
No. Its digits add up to 25, which is not a multiple of 3.
What is special about the number 42991?
42991 is a semiprime: 13 × 3307, the product of two primes.