The number 21188
21188 is a composite number with 6 divisors. Its prime factorisation is × 5297. Divisors (6): 1, 2, 4, 5297, 10594, 21188.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21188 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21188 is composite. Its prime factorisation is
- 3
The divisors add up to 37086; without 21188 itself that is 15898, so 21188 is deficient (15898 is less than 21188). Euler's totient φ(21188) = 10592 numbers up to 21188 share no factor with it.
- 4
The digits of 21188 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 100 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21188 = 2^{2} \times 5297 \]21188 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 37086 |
| Euler totient φ(n) | 10592 |
| Square | 448931344 |
| Cube | 9511957316672 |
| Square root | 145.560984 (= 2√5297) |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 100 |
| Scientific notation | 2.1188 × |
21188 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and eighty-eight |
| Binary (base 2) | 101001011000100 |
| Octal (base 8) | 51304 |
| Hexadecimal (base 16) | 52C4 |
| Base 3 | 1002001202 |
| As time | 21188 seconds = 5 h 53 min 8 s |
Is 21188 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (21188 ÷ 2 = 10594) | 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 (21188 ÷ 4 = 5297) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | 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 | No (remainder 4) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 2) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 2) | 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 21188 a prime number?
No. 21188 = × 5297, so it is divisible by 2.
What are the factors of 21188?
1, 2, 4, 5297, 10594, 21188.
What is 21188 in binary?
101001011000100 (hexadecimal 52C4, octal 51304).
What is the square root of 21188?
About 145.5610, exactly 2√5297.
Is 21188 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 21188?
It is a composite number with 6 divisors.