The number 7791
7791 is a composite number with 12 divisors. Its prime factorisation is 3 × × 53. Divisors (12): 1, 3, 7, 21, 49, 53, 147, 159, 371, 1113, 2597, 7791.
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How to work it out
- 1
7791 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
7791 is composite. Its prime factorisation is
- 3
The divisors add up to 12312; without 7791 itself that is 4521, so 7791 is deficient (4521 is less than 7791). Euler's totient φ(7791) = 4368 numbers up to 7791 share no factor with it.
- 4
The digits of 7791 add up to 24, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 70 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7791 = 3 \times 7^{2} \times 53 \]7791 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 12312 |
| Euler totient φ(n) | 4368 |
| Square | 60699681 |
| Cube | 472911214671 |
| Square root | 88.266641 (= 7√159) |
| Digit sum / digital root | 24 / 6 |
| Collatz steps to 1 | 70 |
| Scientific notation | 7.791 × |
7791 in other forms
| Form | Value |
|---|---|
| In words | seven thousand seven hundred and ninety-one |
| Binary (base 2) | 1111001101111 |
| Octal (base 8) | 17157 |
| Hexadecimal (base 16) | 1E6F |
| Base 3 | 101200120 |
| As time | 7791 seconds = 2 h 9 min 51 s |
Is 7791 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 | Yes (7791 ÷ 3 = 2597) | 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 3) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | Yes (7791 ÷ 7 = 1113) | 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 6) | 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 7791 a prime number?
No. 7791 = 3 × × 53, so it is divisible by 3.
What are the factors of 7791?
1, 3, 7, 21, 49, 53, 147, 159, 371, 1113, 2597, 7791.
What is 7791 in binary?
1111001101111 (hexadecimal 1E6F, octal 17157).
What is the square root of 7791?
About 88.2666, exactly 7√159.
Is 7791 divisible by 3?
Yes. Its digits add up to 24, a multiple of 3.
What is special about the number 7791?
It is a composite number with 12 divisors.