The number 21771
21771 is a composite number with 12 divisors. Its prime factorisation is × 41 × 59. Divisors (12): 1, 3, 9, 41, 59, 123, 177, 369, 531, 2419, 7257, 21771.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21771 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21771 is composite. Its prime factorisation is
- 3
The divisors add up to 32760; without 21771 itself that is 10989, so 21771 is deficient (10989 is less than 21771). Euler's totient φ(21771) = 13920 numbers up to 21771 share no factor with it.
- 4
The digits of 21771 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 193 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21771 = 3^{2} \times 41 \times 59 \]21771 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 32760 |
| Euler totient φ(n) | 13920 |
| Square | 473976441 |
| Cube | 10318941097011 |
| Square root | 147.549992 (= 3√2419) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.1771 × |
21771 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred and seventy-one |
| Binary (base 2) | 101010100001011 |
| Octal (base 8) | 52413 |
| Hexadecimal (base 16) | 550B |
| Base 3 | 1002212100 |
| As time | 21771 seconds = 6 h 2 min 51 s |
Is 21771 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 (21771 ÷ 3 = 7257) | 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 | No (remainder 1) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (21771 ÷ 9 = 2419) | 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 2) | 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 21771 a prime number?
No. 21771 = × 41 × 59, so it is divisible by 3.
What are the factors of 21771?
1, 3, 9, 41, 59, 123, 177, 369, 531, 2419, 7257, 21771.
What is 21771 in binary?
101010100001011 (hexadecimal 550B, octal 52413).
What is the square root of 21771?
About 147.5500, exactly 3√2419.
Is 21771 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 21771?
It is a composite number with 12 divisors.