The number 21495
21495 is a composite number with 8 divisors. Its prime factorisation is 3 × 5 × 1433. Divisors (8): 1, 3, 5, 15, 1433, 4299, 7165, 21495.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21495 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21495 is composite. Its prime factorisation is
- 3
The divisors add up to 34416; without 21495 itself that is 12921, so 21495 is deficient (12921 is less than 21495). Euler's totient φ(21495) = 11456 numbers up to 21495 share no factor with it.
- 4
The digits of 21495 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 100 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21495 = 3 \times 5 \times 1433 \]
21495 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 34416 |
| Euler totient φ(n) | 11456 |
| Square | 462035025 |
| Cube | 9931442862375 |
| Square root | 146.611732 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 100 |
| Scientific notation | 2.1495 × |
21495 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and ninety-five |
| Binary (base 2) | 101001111110111 |
| Octal (base 8) | 51767 |
| Hexadecimal (base 16) | 53F7 |
| Base 3 | 1002111010 |
| As time | 21495 seconds = 5 h 58 min 15 s |
Is 21495 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 (21495 ÷ 3 = 7165) | 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 (21495 ÷ 5 = 4299) | 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 5) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 3) | 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 1) | 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 21495 a prime number?
No. 21495 = 3 × 5 × 1433, so it is divisible by 3.
What are the factors of 21495?
1, 3, 5, 15, 1433, 4299, 7165, 21495.
What is 21495 in binary?
101001111110111 (hexadecimal 53F7, octal 51767).
What is the square root of 21495?
About 146.6117.
Is 21495 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 21495?
It is a composite number with 8 divisors.