The number 21200
21200 is a composite number with 30 divisors. Its prime factorisation is × × 53. Divisors (30): 1, 2, 4, 5, 8, 10, 16, 20, 25, 40, 50, 53, 80, 100, 106, 200 … 21200.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21200: a Harshad number: divisible by its digit sum 5.
- 2
21200 is composite. Its prime factorisation is
- 3
The divisors add up to 51894; without 21200 itself that is 30694, so 21200 is abundant (30694 is more than 21200). Euler's totient φ(21200) = 8320 numbers up to 21200 share no factor with it.
- 4
The digits of 21200 add up to 5, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 30 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21200 = 2^{4} \times 5^{2} \times 53 \]21200 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 30 |
| Sum of divisors | 51894 |
| Euler totient φ(n) | 8320 |
| Square | 449440000 |
| Cube | 9528128000000 |
| Square root | 145.602198 (= 20√53) |
| Digit sum / digital root | 5 / 5 |
| Collatz steps to 1 | 30 |
| Scientific notation | 2.12 × |
21200 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred |
| Binary (base 2) | 101001011010000 |
| Octal (base 8) | 51320 |
| Hexadecimal (base 16) | 52D0 |
| Base 3 | 1002002012 |
| As time | 21200 seconds = 5 h 53 min 20 s |
Is 21200 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21200 ÷ 2 = 10600) | 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 (21200 ÷ 4 = 5300) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21200 ÷ 5 = 4240) | 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 4) | 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 (21200 ÷ 8 = 2650) | 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 | Yes (21200 ÷ 10 = 2120) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | 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 21200 a prime number?
No. 21200 = × × 53, so it is divisible by 2.
What are the factors of 21200?
1, 2, 4, 5, 8, 10, 16, 20, 25, 40, 50, 53, 80, 100, 106, 200, 212, 265, 400, 424, 530, 848, 1060, 1325, 2120, 2650, 4240, 5300, 10600, 21200.
What is 21200 in binary?
101001011010000 (hexadecimal 52D0, octal 51320).
What is the square root of 21200?
About 145.6022, exactly 20√53.
Is 21200 divisible by 3?
No. Its digits add up to 5, which is not a multiple of 3.
What is special about the number 21200?
21200 is a Harshad number: divisible by its digit sum 5.