The number 11987
11987 is the 1438th prime number. Its only divisors are 1 and 11987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 11987: the 1438th prime number.
- 2
11987 is prime, so its only factors are 1 and 11987. It is the 1438th prime; the next prime is 12007 and the one before is 11981.
- 3
The divisors add up to 11988; without 11987 itself that is 1, so 11987 is deficient (1 is less than 11987). Euler's totient φ(11987) = 11986 numbers up to 11987 share no factor with it.
- 4
The digits of 11987 add up to 26, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 81 steps to reach 1.
11987 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 11988 |
| Euler totient φ(n) | 11986 |
| Square | 143688169 |
| Cube | 1722390081803 |
| Square root | 109.485159 |
| Digit sum / digital root | 26 / 8 |
| Collatz steps to 1 | 81 |
| Scientific notation | 1.1987 × |
11987 in other forms
| Form | Value |
|---|---|
| In words | eleven thousand nine hundred and eighty-seven |
| Binary (base 2) | 10111011010011 |
| Octal (base 8) | 27323 |
| Hexadecimal (base 16) | 2ED3 |
| Base 3 | 121102222 |
| As time | 11987 seconds = 3 h 19 min 47 s |
Is 11987 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 2) | 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 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 8) | 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 11987 a prime number?
Yes. 11987 is divisible only by 1 and itself.
What are the factors of 11987?
1, 11987.
What is 11987 in binary?
10111011010011 (hexadecimal 2ED3, octal 27323).
What is the square root of 11987?
About 109.4852.
Is 11987 divisible by 3?
No. Its digits add up to 26, which is not a multiple of 3.
What is special about the number 11987?
11987 is the 1438th prime number.