The number 77765
77765 is a composite number with 8 divisors. Its prime factorisation is 5 × 103 × 151. Divisors (8): 1, 5, 103, 151, 515, 755, 15553, 77765.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 77765: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
77765 is composite. Its prime factorisation is
- 3
The divisors add up to 94848; without 77765 itself that is 17083, so 77765 is deficient (17083 is less than 77765). Euler's totient φ(77765) = 61200 numbers up to 77765 share no factor with it.
- 4
The digits of 77765 add up to 32, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 50 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77765 = 5 \times 103 \times 151 \]
77765 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 94848 |
| Euler totient φ(n) | 61200 |
| Square | 6047395225 |
| Cube | 470275689672125 |
| Square root | 278.863766 |
| Digit sum / digital root | 32 / 5 |
| Collatz steps to 1 | 50 |
| Scientific notation | 7.7765 × |
77765 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand seven hundred and sixty-five |
| Binary (base 2) | 10010111111000101 |
| Octal (base 8) | 227705 |
| Hexadecimal (base 16) | 12FC5 |
| Base 3 | 10221200012 |
| As time | 77765 seconds = 21 h 36 min 5 s |
Is 77765 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 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (77765 ÷ 5 = 15553) | 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 | No (remainder 2) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 77765 a prime number?
No. 77765 = 5 × 103 × 151, so it is divisible by 5.
What are the factors of 77765?
1, 5, 103, 151, 515, 755, 15553, 77765.
What is 77765 in binary?
10010111111000101 (hexadecimal 12FC5, octal 227705).
What is the square root of 77765?
About 278.8638.
Is 77765 divisible by 3?
No. Its digits add up to 32, which is not a multiple of 3.
What is special about the number 77765?
77765 is a happy number: repeatedly adding the squares of its digits reaches 1.