The number 77791
77791 is a composite number with 4 divisors. Its prime factorisation is 7 × 11113. Divisors (4): 1, 7, 11113, 77791.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 77791: a semiprime: 7 × 11113, the product of two primes.
- 2
77791 is composite. Its prime factorisation is
- 3
The divisors add up to 88912; without 77791 itself that is 11121, so 77791 is deficient (11121 is less than 77791). Euler's totient φ(77791) = 66672 numbers up to 77791 share no factor with it.
- 4
The digits of 77791 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 169 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77791 = 7 \times 11113 \]
77791 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 88912 |
| Euler totient φ(n) | 66672 |
| Square | 6051439681 |
| Cube | 470747544224671 |
| Square root | 278.910380 |
| Digit sum / digital root | 31 / 4 |
| Collatz steps to 1 | 169 |
| Scientific notation | 7.7791 × |
77791 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand seven hundred and ninety-one |
| Binary (base 2) | 10010111111011111 |
| Octal (base 8) | 227737 |
| Hexadecimal (base 16) | 12FDF |
| Base 3 | 10221201011 |
| As time | 77791 seconds = 21 h 36 min 31 s |
Is 77791 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 | Yes (77791 ÷ 7 = 11113) | 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 7) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | 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 77791 a prime number?
No. 77791 = 7 × 11113, so it is divisible by 7.
What are the factors of 77791?
1, 7, 11113, 77791.
What is 77791 in binary?
10010111111011111 (hexadecimal 12FDF, octal 227737).
What is the square root of 77791?
About 278.9104.
Is 77791 divisible by 3?
No. Its digits add up to 31, which is not a multiple of 3.
What is special about the number 77791?
77791 is a semiprime: 7 × 11113, the product of two primes.