The number 21195
21195 is a composite number with 16 divisors. Its prime factorisation is × 5 × 157. Divisors (16): 1, 3, 5, 9, 15, 27, 45, 135, 157, 471, 785, 1413, 2355, 4239, 7065, 21195.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21195 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21195 is composite. Its prime factorisation is
- 3
The divisors add up to 37920; without 21195 itself that is 16725, so 21195 is deficient (16725 is less than 21195). Euler's totient φ(21195) = 11232 numbers up to 21195 share no factor with it.
- 4
The digits of 21195 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 56 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21195 = 3^{3} \times 5 \times 157 \]21195 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 16 |
| Sum of divisors | 37920 |
| Euler totient φ(n) | 11232 |
| Square | 449228025 |
| Cube | 9521387989875 |
| Square root | 145.585027 (= 3√2355) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 56 |
| Scientific notation | 2.1195 × |
21195 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand one hundred and ninety-five |
| Binary (base 2) | 101001011001011 |
| Octal (base 8) | 51313 |
| Hexadecimal (base 16) | 52CB |
| Base 3 | 1002002000 |
| As time | 21195 seconds = 5 h 53 min 15 s |
Is 21195 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | No (remainder 1) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | Yes (21195 ÷ 3 = 7065) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21195 ÷ 5 = 4239) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 3) | 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 3) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (21195 ÷ 9 = 2355) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21195 a prime number?
No. 21195 = × 5 × 157, so it is divisible by 3.
What are the factors of 21195?
1, 3, 5, 9, 15, 27, 45, 135, 157, 471, 785, 1413, 2355, 4239, 7065, 21195.
What is 21195 in binary?
101001011001011 (hexadecimal 52CB, octal 51313).
What is the square root of 21195?
About 145.5850, exactly 3√2355.
Is 21195 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 21195?
It is a composite number with 16 divisors.