The number 11971
11971 is a twin prime (11969 and 11971 are both prime) and the 1436th prime number. Its only divisors are 1 and 11971.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 11971: a twin prime (11969 and 11971 are both prime); the 1436th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
11971 is prime, so its only factors are 1 and 11971. It is the 1436th prime; the next prime is 11981 and the one before is 11969.
- 3
The divisors add up to 11972; without 11971 itself that is 1, so 11971 is deficient (1 is less than 11971). Euler's totient φ(11971) = 11970 numbers up to 11971 share no factor with it.
- 4
The digits of 11971 add up to 19, and repeating that until one digit is left gives the digital root 1. The Collatz sequence (halve if even, else 3n+1) takes 94 steps to reach 1.
11971 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 11972 |
| Euler totient φ(n) | 11970 |
| Square | 143304841 |
| Cube | 1715502251611 |
| Square root | 109.412065 |
| Digit sum / digital root | 19 / 1 |
| Collatz steps to 1 | 94 |
| Scientific notation | 1.1971 × |
11971 in other forms
| Form | Value |
|---|---|
| In words | eleven thousand nine hundred and seventy-one |
| Binary (base 2) | 10111011000011 |
| Octal (base 8) | 27303 |
| Hexadecimal (base 16) | 2EC3 |
| Base 3 | 121102101 |
| As time | 11971 seconds = 3 h 19 min 31 s |
Is 11971 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 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 1) | 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 11971 a prime number?
Yes. 11971 is divisible only by 1 and itself.
What are the factors of 11971?
1, 11971.
What is 11971 in binary?
10111011000011 (hexadecimal 2EC3, octal 27303).
What is the square root of 11971?
About 109.4121.
Is 11971 divisible by 3?
No. Its digits add up to 19, which is not a multiple of 3.
What is special about the number 11971?
11971 is a twin prime (11969 and 11971 are both prime); the 1436th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.