The number 21275
21275 is a composite number with 12 divisors. Its prime factorisation is × 23 × 37. Divisors (12): 1, 5, 23, 25, 37, 115, 185, 575, 851, 925, 4255, 21275.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21275 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21275 is composite. Its prime factorisation is
- 3
The divisors add up to 28272; without 21275 itself that is 6997, so 21275 is deficient (6997 is less than 21275). Euler's totient φ(21275) = 15840 numbers up to 21275 share no factor with it.
- 4
The digits of 21275 add up to 17, 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
\[ 21275 = 5^{2} \times 23 \times 37 \]21275 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 28272 |
| Euler totient φ(n) | 15840 |
| Square | 452625625 |
| Cube | 9629610171875 |
| Square root | 145.859521 (= 5√851) |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.1275 × |
21275 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred and seventy-five |
| Binary (base 2) | 101001100011011 |
| Octal (base 8) | 51433 |
| Hexadecimal (base 16) | 531B |
| Base 3 | 1002011222 |
| As time | 21275 seconds = 5 h 54 min 35 s |
Is 21275 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 | No (remainder 2) | 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 (21275 ÷ 5 = 4255) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 2) | 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 | No (remainder 8) | 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 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21275 a prime number?
No. 21275 = × 23 × 37, so it is divisible by 5.
What are the factors of 21275?
1, 5, 23, 25, 37, 115, 185, 575, 851, 925, 4255, 21275.
What is 21275 in binary?
101001100011011 (hexadecimal 531B, octal 51433).
What is the square root of 21275?
About 145.8595, exactly 5√851.
Is 21275 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 21275?
It is a composite number with 12 divisors.