The number 71987
71987 is the 7126th prime number. Its only divisors are 1 and 71987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 71987: the 7126th prime number.
- 2
71987 is prime, so its only factors are 1 and 71987. It is the 7126th prime; the next prime is 71993 and the one before is 71983.
- 3
The divisors add up to 71988; without 71987 itself that is 1, so 71987 is deficient (1 is less than 71987). Euler's totient φ(71987) = 71986 numbers up to 71987 share no factor with it.
- 4
The digits of 71987 add up to 32, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 187 steps to reach 1.
71987 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 71988 |
| Euler totient φ(n) | 71986 |
| Square | 5182128169 |
| Cube | 373045860501803 |
| Square root | 268.303932 |
| Digit sum / digital root | 32 / 5 |
| Collatz steps to 1 | 187 |
| Scientific notation | 7.1987 × |
71987 in other forms
| Form | Value |
|---|---|
| In words | seventy-one thousand nine hundred and eighty-seven |
| Binary (base 2) | 10001100100110011 |
| Octal (base 8) | 214463 |
| Hexadecimal (base 16) | 11933 |
| Base 3 | 10122202012 |
| As time | 71987 seconds = 19 h 59 min 47 s |
Is 71987 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 6) | 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 5) | 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 3) | 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 71987 a prime number?
Yes. 71987 is divisible only by 1 and itself.
What are the factors of 71987?
1, 71987.
What is 71987 in binary?
10001100100110011 (hexadecimal 11933, octal 214463).
What is the square root of 71987?
About 268.3039.
Is 71987 divisible by 3?
No. Its digits add up to 32, which is not a multiple of 3.
What is special about the number 71987?
71987 is the 7126th prime number.