The number 42491
42491 is the 4446th prime number. Its only divisors are 1 and 42491.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 42491: the 4446th prime number.
- 2
42491 is prime, so its only factors are 1 and 42491. It is the 4446th prime; the next prime is 42499 and the one before is 42487.
- 3
The divisors add up to 42492; without 42491 itself that is 1, so 42491 is deficient (1 is less than 42491). Euler's totient φ(42491) = 42490 numbers up to 42491 share no factor with it.
- 4
The digits of 42491 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 101 steps to reach 1.
42491 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 42492 |
| Euler totient φ(n) | 42490 |
| Square | 1805485081 |
| Cube | 76716866576771 |
| Square root | 206.133452 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 101 |
| Scientific notation | 4.2491 × |
42491 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand four hundred and ninety-one |
| Binary (base 2) | 1010010111111011 |
| Octal (base 8) | 122773 |
| Hexadecimal (base 16) | A5FB |
| Base 3 | 2011021202 |
| As time | 42491 seconds = 11 h 48 min 11 s |
Is 42491 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 1) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | 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 9) | 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 42491 a prime number?
Yes. 42491 is divisible only by 1 and itself.
What are the factors of 42491?
1, 42491.
What is 42491 in binary?
1010010111111011 (hexadecimal A5FB, octal 122773).
What is the square root of 42491?
About 206.1335.
Is 42491 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 42491?
42491 is the 4446th prime number.