The number 21184
21184 is a composite number with 14 divisors. Its prime factorisation is × 331. Divisors (14): 1, 2, 4, 8, 16, 32, 64, 331, 662, 1324, 2648, 5296, 10592, 21184.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21184: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 16.
- 2
21184 is composite. Its prime factorisation is
- 3
The divisors add up to 42164; without 21184 itself that is 20980, so 21184 is deficient (20980 is less than 21184). Euler's totient φ(21184) = 10560 numbers up to 21184 share no factor with it.
- 4
The digits of 21184 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21184 = 2^{6} \times 331 \]21184 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 14 |
| Sum of divisors | 42164 |
| Euler totient φ(n) | 10560 |
| Square | 448761856 |
| Cube | 9506571157504 |
| Square root | 145.547243 (= 8√331) |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 30 |
| Scientific notation | 2.1184 × |
21184 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and eighty-four |
| Binary (base 2) | 101001011000000 |
| Octal (base 8) | 51300 |
| Hexadecimal (base 16) | 52C0 |
| Base 3 | 1002001121 |
| As time | 21184 seconds = 5 h 53 min 4 s |
Is 21184 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21184 ÷ 2 = 10592) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 1) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21184 ÷ 4 = 5296) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 4) | 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 | Yes (21184 ÷ 8 = 2648) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 4) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 4) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21184 a prime number?
No. 21184 = × 331, so it is divisible by 2.
What are the factors of 21184?
1, 2, 4, 8, 16, 32, 64, 331, 662, 1324, 2648, 5296, 10592, 21184.
What is 21184 in binary?
101001011000000 (hexadecimal 52C0, octal 51300).
What is the square root of 21184?
About 145.5472, exactly 8√331.
Is 21184 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 21184?
21184 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 16.