The number 21604
21604 is a composite number with 12 divisors. Its prime factorisation is × 11 × 491. Divisors (12): 1, 2, 4, 11, 22, 44, 491, 982, 1964, 5401, 10802, 21604.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21604 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21604 is composite. Its prime factorisation is
- 3
The divisors add up to 41328; without 21604 itself that is 19724, so 21604 is deficient (19724 is less than 21604). Euler's totient φ(21604) = 9800 numbers up to 21604 share no factor with it.
- 4
The digits of 21604 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 162 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21604 = 2^{2} \times 11 \times 491 \]21604 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 41328 |
| Euler totient φ(n) | 9800 |
| Square | 466732816 |
| Cube | 10083295756864 |
| Square root | 146.982992 (= 2√5401) |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 162 |
| Scientific notation | 2.1604 × |
21604 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand six hundred and four |
| Binary (base 2) | 101010001100100 |
| Octal (base 8) | 52144 |
| Hexadecimal (base 16) | 5464 |
| Base 3 | 1002122011 |
| As time | 21604 seconds = 6 h 0 min 4 s |
Is 21604 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21604 ÷ 2 = 10802) | 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 (21604 ÷ 4 = 5401) | 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 | No (remainder 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 4) | 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 | Yes (21604 ÷ 11 = 1964) | 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 21604 a prime number?
No. 21604 = × 11 × 491, so it is divisible by 2.
What are the factors of 21604?
1, 2, 4, 11, 22, 44, 491, 982, 1964, 5401, 10802, 21604.
What is 21604 in binary?
101010001100100 (hexadecimal 5464, octal 52144).
What is the square root of 21604?
About 146.9830, exactly 2√5401.
Is 21604 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 21604?
It is a composite number with 12 divisors.