The number 28221
28221 is a composite number with 8 divisors. Its prime factorisation is 3 × 23 × 409. Divisors (8): 1, 3, 23, 69, 409, 1227, 9407, 28221.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
28221 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
28221 is composite. Its prime factorisation is
- 3
The divisors add up to 39360; without 28221 itself that is 11139, so 28221 is deficient (11139 is less than 28221). Euler's totient φ(28221) = 17952 numbers up to 28221 share no factor with it.
- 4
The digits of 28221 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 59 steps to reach 1.
LaTeX source of the formulas on this page
\[ 28221 = 3 \times 23 \times 409 \]
28221 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 39360 |
| Euler totient φ(n) | 17952 |
| Square | 796424841 |
| Cube | 22475905437861 |
| Square root | 167.991071 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 59 |
| Scientific notation | 2.8221 × |
28221 in other forms
| Form | Value |
|---|---|
| In words | twenty-eight thousand two hundred and twenty-one |
| Binary (base 2) | 110111000111101 |
| Octal (base 8) | 67075 |
| Hexadecimal (base 16) | 6E3D |
| Base 3 | 1102201020 |
| As time | 28221 seconds = 7 h 50 min 21 s |
Is 28221 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 (28221 ÷ 3 = 9407) | 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 | No (remainder 1) | 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 4) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 6) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 1) | 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 28221 a prime number?
No. 28221 = 3 × 23 × 409, so it is divisible by 3.
What are the factors of 28221?
1, 3, 23, 69, 409, 1227, 9407, 28221.
What is 28221 in binary?
110111000111101 (hexadecimal 6E3D, octal 67075).
What is the square root of 28221?
About 167.9911.
Is 28221 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 28221?
It is a composite number with 8 divisors.