The number 21204
21204 is a composite number with 36 divisors. Its prime factorisation is × × 19 × 31. Divisors (36): 1, 2, 3, 4, 6, 9, 12, 18, 19, 31, 36, 38, 57, 62, 76, 93 … 21204.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21204: a Harshad number: divisible by its digit sum 9.
- 2
21204 is composite. Its prime factorisation is
- 3
The divisors add up to 58240; without 21204 itself that is 37036, so 21204 is abundant (37036 is more than 21204). Euler's totient φ(21204) = 6480 numbers up to 21204 share no factor with it.
- 4
The digits of 21204 add up to 9, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21204 = 2^{2} \times 3^{2} \times 19 \times 31 \]21204 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 36 |
| Sum of divisors | 58240 |
| Euler totient φ(n) | 6480 |
| Square | 449609616 |
| Cube | 9533522297664 |
| Square root | 145.615933 (= 6√589) |
| Digit sum / digital root | 9 / 9 |
| Collatz steps to 1 | 30 |
| Scientific notation | 2.1204 × |
21204 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred and four |
| Binary (base 2) | 101001011010100 |
| Octal (base 8) | 51324 |
| Hexadecimal (base 16) | 52D4 |
| Base 3 | 1002002100 |
| As time | 21204 seconds = 5 h 53 min 24 s |
Is 21204 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21204 ÷ 2 = 10602) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21204 ÷ 3 = 7068) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | Yes (21204 ÷ 4 = 5301) | 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 | Yes (21204 ÷ 6 = 3534) | 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 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (21204 ÷ 9 = 2356) | 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 7) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | Yes (21204 ÷ 12 = 1767) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21204 a prime number?
No. 21204 = × × 19 × 31, so it is divisible by 2.
What are the factors of 21204?
1, 2, 3, 4, 6, 9, 12, 18, 19, 31, 36, 38, 57, 62, 76, 93, 114, 124, 171, 186, 228, 279, 342, 372, 558, 589, 684, 1116, 1178, 1767, 2356, 3534, 5301, 7068, 10602, 21204.
What is 21204 in binary?
101001011010100 (hexadecimal 52D4, octal 51324).
What is the square root of 21204?
About 145.6159, exactly 6√589.
Is 21204 divisible by 3?
Yes. Its digits add up to 9, a multiple of 3.
What is special about the number 21204?
21204 is a Harshad number: divisible by its digit sum 9.