The number 42191
42191 is a composite number with 4 divisors. Its prime factorisation is 31 × 1361. Divisors (4): 1, 31, 1361, 42191.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42191: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 31 × 1361, the product of two primes.
- 2
42191 is composite. Its prime factorisation is
- 3
The divisors add up to 43584; without 42191 itself that is 1393, so 42191 is deficient (1393 is less than 42191). Euler's totient φ(42191) = 40800 numbers up to 42191 share no factor with it.
- 4
The digits of 42191 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 44 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42191 = 31 \times 1361 \]
42191 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 43584 |
| Euler totient φ(n) | 40800 |
| Square | 1780080481 |
| Cube | 75103375573871 |
| Square root | 205.404479 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 44 |
| Scientific notation | 4.2191 × |
42191 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand one hundred and ninety-one |
| Binary (base 2) | 1010010011001111 |
| Octal (base 8) | 122317 |
| Hexadecimal (base 16) | A4CF |
| Base 3 | 2010212122 |
| As time | 42191 seconds = 11 h 43 min 11 s |
Is 42191 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 | 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 8) | 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 6) | 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 42191 a prime number?
No. 42191 = 31 × 1361, so it is divisible by 31.
What are the factors of 42191?
1, 31, 1361, 42191.
What is 42191 in binary?
1010010011001111 (hexadecimal A4CF, octal 122317).
What is the square root of 42191?
About 205.4045.
Is 42191 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 42191?
42191 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 31 × 1361, the product of two primes.