The number 21225
21225 is a composite number with 12 divisors. Its prime factorisation is 3 × × 283. Divisors (12): 1, 3, 5, 15, 25, 75, 283, 849, 1415, 4245, 7075, 21225.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
21225 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
21225 is composite. Its prime factorisation is
- 3
The divisors add up to 35216; without 21225 itself that is 13991, so 21225 is deficient (13991 is less than 21225). Euler's totient φ(21225) = 11280 numbers up to 21225 share no factor with it.
- 4
The digits of 21225 add up to 12, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 224 steps to reach 1.
LaTeX source of the formulas on this page
\[ 21225 = 3 \times 5^{2} \times 283 \]21225 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 35216 |
| Euler totient φ(n) | 11280 |
| Square | 450500625 |
| Cube | 9561875765625 |
| Square root | 145.688023 (= 5√849) |
| Digit sum / digital root | 12 / 3 |
| Collatz steps to 1 | 224 |
| Scientific notation | 2.1225 × |
21225 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand two hundred and twenty-five |
| Binary (base 2) | 101001011101001 |
| Octal (base 8) | 51351 |
| Hexadecimal (base 16) | 52E9 |
| Base 3 | 1002010010 |
| As time | 21225 seconds = 5 h 53 min 45 s |
Is 21225 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 (21225 ÷ 3 = 7075) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 1) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (21225 ÷ 5 = 4245) | 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 1) | 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 1) | 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 6) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21225 a prime number?
No. 21225 = 3 × × 283, so it is divisible by 3.
What are the factors of 21225?
1, 3, 5, 15, 25, 75, 283, 849, 1415, 4245, 7075, 21225.
What is 21225 in binary?
101001011101001 (hexadecimal 52E9, octal 51351).
What is the square root of 21225?
About 145.6880, exactly 5√849.
Is 21225 divisible by 3?
Yes. Its digits add up to 12, a multiple of 3.
What is special about the number 21225?
It is a composite number with 12 divisors.