The number 77721
77721 is a composite number with 8 divisors. Its prime factorisation is 3 × 7 × 3701. Divisors (8): 1, 3, 7, 21, 3701, 11103, 25907, 77721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
77721 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
77721 is composite. Its prime factorisation is
- 3
The divisors add up to 118464; without 77721 itself that is 40743, so 77721 is deficient (40743 is less than 77721). Euler's totient φ(77721) = 44400 numbers up to 77721 share no factor with it.
- 4
The digits of 77721 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 169 steps to reach 1.
LaTeX source of the formulas on this page
\[ 77721 = 3 \times 7 \times 3701 \]
77721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 118464 |
| Euler totient φ(n) | 44400 |
| Square | 6040553841 |
| Cube | 469477885076361 |
| Square root | 278.784863 |
| Digit sum / digital root | 24 / 6 |
| Collatz steps to 1 | 169 |
| Scientific notation | 7.7721 × |
77721 in other forms
| Form | Value |
|---|---|
| In words | seventy-seven thousand seven hundred and twenty-one |
| Binary (base 2) | 10010111110011001 |
| Octal (base 8) | 227631 |
| Hexadecimal (base 16) | 12F99 |
| Base 3 | 10221121120 |
| As time | 77721 seconds = 21 h 35 min 21 s |
Is 77721 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 (77721 ÷ 3 = 25907) | 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 | Yes (77721 ÷ 7 = 11103) | 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 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 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 77721 a prime number?
No. 77721 = 3 × 7 × 3701, so it is divisible by 3.
What are the factors of 77721?
1, 3, 7, 21, 3701, 11103, 25907, 77721.
What is 77721 in binary?
10010111110011001 (hexadecimal 12F99, octal 227631).
What is the square root of 77721?
About 278.7849.
Is 77721 divisible by 3?
Yes. Its digits add up to 24, a multiple of 3.
What is special about the number 77721?
It is a composite number with 8 divisors.