The number 21104
21104 is a composite number with 10 divisors. Its prime factorisation is × 1319. Divisors (10): 1, 2, 4, 8, 16, 1319, 2638, 5276, 10552, 21104.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21104: a Harshad number: divisible by its digit sum 8.
- 2
21104 is composite. Its prime factorisation is
- 3
The divisors add up to 40920; without 21104 itself that is 19816, so 21104 is deficient (19816 is less than 21104). Euler's totient φ(21104) = 10544 numbers up to 21104 share no factor with it.
- 4
The digits of 21104 add up to 8, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 149 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21104 = 2^{4} \times 1319 \]21104 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 10 |
| Sum of divisors | 40920 |
| Euler totient φ(n) | 10544 |
| Square | 445378816 |
| Cube | 9399274532864 |
| Square root | 145.272158 (= 4√1319) |
| Digit sum / digital root | 8 / 8 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.1104 × |
21104 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and four |
| Binary (base 2) | 101001001110000 |
| Octal (base 8) | 51160 |
| Hexadecimal (base 16) | 5270 |
| Base 3 | 1001221122 |
| As time | 21104 seconds = 5 h 51 min 44 s |
Is 21104 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21104 ÷ 2 = 10552) | 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 (21104 ÷ 4 = 5276) | 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 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 (21104 ÷ 8 = 2638) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 8) | 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 6) | 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 21104 a prime number?
No. 21104 = × 1319, so it is divisible by 2.
What are the factors of 21104?
1, 2, 4, 8, 16, 1319, 2638, 5276, 10552, 21104.
What is 21104 in binary?
101001001110000 (hexadecimal 5270, octal 51160).
What is the square root of 21104?
About 145.2722, exactly 4√1319.
Is 21104 divisible by 3?
No. Its digits add up to 8, which is not a multiple of 3.
What is special about the number 21104?
21104 is a Harshad number: divisible by its digit sum 8.