The number 77745
77745 is a composite number with 16 divisors. Its prime factorisation is 3 × 5 × 71 × 73. Divisors (16): 1, 3, 5, 15, 71, 73, 213, 219, 355, 365, 1065, 1095, 5183, 15549, 25915, 77745.
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How to work it out
- 1
What is special about 77745: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
77745 is composite. Its prime factorisation is
- 3
The divisors add up to 127872; without 77745 itself that is 50127, so 77745 is deficient (50127 is less than 77745). Euler's totient φ(77745) = 40320 numbers up to 77745 share no factor with it.
- 4
The digits of 77745 add up to 30, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 50 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77745 = 3 \times 5 \times 71 \times 73 \]
77745 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 127872 |
| Euler totient φ(n) | 40320 |
| Square | 6044285025 |
| Cube | 469912939268625 |
| Square root | 278.827904 |
| Digit sum / digital root | 30 / 3 |
| Collatz steps to 1 | 50 |
| Scientific notation | 7.7745 × |
77745 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand seven hundred and forty-five |
| Binary (base 2) | 10010111110110001 |
| Octal (base 8) | 227661 |
| Hexadecimal (base 16) | 12FB1 |
| Base 3 | 10221122110 |
| As time | 77745 seconds = 21 h 35 min 45 s |
Is 77745 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 (77745 ÷ 3 = 25915) | 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 (77745 ÷ 5 = 15549) | 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 3) | 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 5) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 77745 a prime number?
No. 77745 = 3 × 5 × 71 × 73, so it is divisible by 3.
What are the factors of 77745?
1, 3, 5, 15, 71, 73, 213, 219, 355, 365, 1065, 1095, 5183, 15549, 25915, 77745.
What is 77745 in binary?
10010111110110001 (hexadecimal 12FB1, octal 227661).
What is the square root of 77745?
About 278.8279.
Is 77745 divisible by 3?
Yes. Its digits add up to 30, a multiple of 3.
What is special about the number 77745?
77745 is a happy number: repeatedly adding the squares of its digits reaches 1.