The number 77987
77987 is a composite number with 8 divisors. Its prime factorisation is 7 × 13 × 857. Divisors (8): 1, 7, 13, 91, 857, 5999, 11141, 77987.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
77987 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
77987 is composite. Its prime factorisation is
- 3
The divisors add up to 96096; without 77987 itself that is 18109, so 77987 is deficient (18109 is less than 77987). Euler's totient φ(77987) = 61632 numbers up to 77987 share no factor with it.
- 4
The digits of 77987 add up to 38, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 125 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77987 = 7 \times 13 \times 857 \]
77987 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 96096 |
| Euler totient φ(n) | 61632 |
| Square | 6081972169 |
| Cube | 474314763543803 |
| Square root | 279.261526 |
| Digit sum / digital root | 38 / 2 |
| Collatz steps to 1 | 125 |
| Scientific notation | 7.7987 × |
77987 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand nine hundred and eighty-seven |
| Binary (base 2) | 10011000010100011 |
| Octal (base 8) | 230243 |
| Hexadecimal (base 16) | 130A3 |
| Base 3 | 10221222102 |
| As time | 77987 seconds = 21 h 39 min 47 s |
Is 77987 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 | Yes (77987 ÷ 7 = 11141) | 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 2) | 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 77987 a prime number?
No. 77987 = 7 × 13 × 857, so it is divisible by 7.
What are the factors of 77987?
1, 7, 13, 91, 857, 5999, 11141, 77987.
What is 77987 in binary?
10011000010100011 (hexadecimal 130A3, octal 230243).
What is the square root of 77987?
About 279.2615.
Is 77987 divisible by 3?
No. Its digits add up to 38, which is not a multiple of 3.
What is special about the number 77987?
It is a composite number with 8 divisors.