The number 12491
12491 is the 1491st prime number. Its only divisors are 1 and 12491.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 12491: the 1491st prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
12491 is prime, so its only factors are 1 and 12491. It is the 1491st prime; the next prime is 12497 and the one before is 12487.
- 3
The divisors add up to 12492; without 12491 itself that is 1, so 12491 is deficient (1 is less than 12491). Euler's totient φ(12491) = 12490 numbers up to 12491 share no factor with it.
- 4
The digits of 12491 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 63 steps to reach 1.
12491 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 12492 |
| Euler totient φ(n) | 12490 |
| Square | 156025081 |
| Cube | 1948909286771 |
| Square root | 111.763142 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 63 |
| Scientific notation | 1.2491 × |
12491 in other forms
| Form | Value |
|---|---|
| In words | twelve thousand four hundred and ninety-one |
| Binary (base 2) | 11000011001011 |
| Octal (base 8) | 30313 |
| Hexadecimal (base 16) | 30CB |
| Base 3 | 122010122 |
| As time | 12491 seconds = 3 h 28 min 11 s |
Is 12491 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 3) | 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 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 12491 a prime number?
Yes. 12491 is divisible only by 1 and itself.
What are the factors of 12491?
1, 12491.
What is 12491 in binary?
11000011001011 (hexadecimal 30CB, octal 30313).
What is the square root of 12491?
About 111.7631.
Is 12491 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 12491?
12491 is the 1491st prime number; a happy number: repeatedly adding the squares of its digits reaches 1.