The number 7987
7987 is a composite number with 6 divisors. Its prime factorisation is Ć 163. Divisors (6): 1, 7, 49, 163, 1141, 7987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
7987 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
7987 is composite. Its prime factorisation is
- 3
The divisors add up to 9348; without 7987 itself that is 1361, so 7987 is deficient (1361 is less than 7987). Euler's totient Ļ(7987) = 6804 numbers up to 7987 share no factor with it.
- 4
The digits of 7987 add up to 31, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 52 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7987 = 7^{2} \times 163 \]7987 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 9348 |
| Euler totient Ļ(n) | 6804 |
| Square | 63792169 |
| Cube | 509508053803 |
| Square root | 89.370017 (= 7ā163) |
| Digit sum / digital root | 31 / 4 |
| Collatz steps to 1 | 52 |
| Scientific notation | 7.987 Ć |
7987 in other forms
| Form | Value |
|---|---|
| In words | seven thousand nine hundred and eighty-seven |
| Binary (base 2) | 1111100110011 |
| Octal (base 8) | 17463 |
| Hexadecimal (base 16) | 1F33 |
| Base 3 | 101221211 |
| As time | 7987 seconds = 2 h 13 min 7 s |
Is 7987 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 2) | 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 | Yes (7987 Ć· 7 = 1141) | 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 4) | 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 1) | 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 7987 a prime number?
No. 7987 = Ć 163, so it is divisible by 7.
What are the factors of 7987?
1, 7, 49, 163, 1141, 7987.
What is 7987 in binary?
1111100110011 (hexadecimal 1F33, octal 17463).
What is the square root of 7987?
About 89.3700, exactly 7ā163.
Is 7987 divisible by 3?
No. Its digits add up to 31, which is not a multiple of 3.
What is special about the number 7987?
It is a composite number with 6 divisors.