The number 21776
21776 is a composite number with 10 divisors. Its prime factorisation is × 1361. Divisors (10): 1, 2, 4, 8, 16, 1361, 2722, 5444, 10888, 21776.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21776: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21776 is composite. Its prime factorisation is
- 3
The divisors add up to 42222; without 21776 itself that is 20446, so 21776 is deficient (20446 is less than 21776). Euler's totient φ(21776) = 10880 numbers up to 21776 share no factor with it.
- 4
The digits of 21776 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21776 = 2^{4} \times 1361 \]21776 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 10 |
| Sum of divisors | 42222 |
| Euler totient φ(n) | 10880 |
| Square | 474194176 |
| Cube | 10326052376576 |
| Square root | 147.566934 (= 4√1361) |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1776 × |
21776 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand seven hundred and seventy-six |
| Binary (base 2) | 101010100010000 |
| Octal (base 8) | 52420 |
| Hexadecimal (base 16) | 5510 |
| Base 3 | 1002212112 |
| As time | 21776 seconds = 6 h 2 min 56 s |
Is 21776 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21776 ÷ 2 = 10888) | 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 | Yes (21776 ÷ 4 = 5444) | 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 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 | Yes (21776 ÷ 8 = 2722) | 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 6) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 8) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21776 a prime number?
No. 21776 = × 1361, so it is divisible by 2.
What are the factors of 21776?
1, 2, 4, 8, 16, 1361, 2722, 5444, 10888, 21776.
What is 21776 in binary?
101010100010000 (hexadecimal 5510, octal 52420).
What is the square root of 21776?
About 147.5669, exactly 4√1361.
Is 21776 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 21776?
21776 is a happy number: repeatedly adding the squares of its digits reaches 1.