The number 7761
7761 is a composite number with 8 divisors. Its prime factorisation is 3 × 13 × 199. Divisors (8): 1, 3, 13, 39, 199, 597, 2587, 7761.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
7761 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
7761 is composite. Its prime factorisation is
- 3
The divisors add up to 11200; without 7761 itself that is 3439, so 7761 is deficient (3439 is less than 7761). Euler's totient φ(7761) = 4752 numbers up to 7761 share no factor with it.
- 4
The digits of 7761 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 145 steps to reach 1.
LaTeX source of the formulas on this page
\[ 7761 = 3 \times 13 \times 199 \]
7761 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 11200 |
| Euler totient φ(n) | 4752 |
| Square | 60233121 |
| Cube | 467469252081 |
| Square root | 88.096538 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 145 |
| Scientific notation | 7.761 × |
7761 in other forms
| Form | Value |
|---|---|
| In words | seven thousand seven hundred and sixty-one |
| Binary (base 2) | 1111001010001 |
| Octal (base 8) | 17121 |
| Hexadecimal (base 16) | 1E51 |
| Base 3 | 101122110 |
| As time | 7761 seconds = 2 h 9 min 21 s |
Is 7761 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 (7761 ÷ 3 = 2587) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | 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 | No (remainder 5) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 7761 a prime number?
No. 7761 = 3 × 13 × 199, so it is divisible by 3.
What are the factors of 7761?
1, 3, 13, 39, 199, 597, 2587, 7761.
What is 7761 in binary?
1111001010001 (hexadecimal 1E51, octal 17121).
What is the square root of 7761?
About 88.0965.
Is 7761 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 7761?
It is a composite number with 8 divisors.