The number 27921
27921 is a composite number with 8 divisors. Its prime factorisation is 3 × 41 × 227. Divisors (8): 1, 3, 41, 123, 227, 681, 9307, 27921.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 27921: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
27921 is composite. Its prime factorisation is
- 3
The divisors add up to 38304; without 27921 itself that is 10383, so 27921 is deficient (10383 is less than 27921). Euler's totient φ(27921) = 18080 numbers up to 27921 share no factor with it.
- 4
The digits of 27921 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 90 steps to reach 1.
LaTeX source of the formulas on this page
\[ 27921 = 3 \times 41 \times 227 \]
27921 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 38304 |
| Euler totient φ(n) | 18080 |
| Square | 779582241 |
| Cube | 21766715750961 |
| Square root | 167.095781 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 90 |
| Scientific notation | 2.7921 × |
27921 in other forms
| Form | Value |
|---|---|
| In words | twenty-seven thousand nine hundred and twenty-one |
| Binary (base 2) | 110110100010001 |
| Octal (base 8) | 66421 |
| Hexadecimal (base 16) | 6D11 |
| Base 3 | 1102022010 |
| As time | 27921 seconds = 7 h 45 min 21 s |
Is 27921 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 (27921 ÷ 3 = 9307) | 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 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 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 3) | 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 27921 a prime number?
No. 27921 = 3 × 41 × 227, so it is divisible by 3.
What are the factors of 27921?
1, 3, 41, 123, 227, 681, 9307, 27921.
What is 27921 in binary?
110110100010001 (hexadecimal 6D11, octal 66421).
What is the square root of 27921?
About 167.0958.
Is 27921 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 27921?
27921 is a happy number: repeatedly adding the squares of its digits reaches 1.