The number 38821
38821 is the 4090th prime number. Its only divisors are 1 and 38821.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 38821: the 4090th prime number.
- 2
38821 is prime, so its only factors are 1 and 38821. It is the 4090th prime; the next prime is 38833 and the one before is 38803.
- 3
The divisors add up to 38822; without 38821 itself that is 1, so 38821 is deficient (1 is less than 38821). Euler's totient φ(38821) = 38820 numbers up to 38821 share no factor with it.
- 4
The digits of 38821 add up to 22, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 181 steps to reach 1.
38821 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 38822 |
| Euler totient φ(n) | 38820 |
| Square | 1507070041 |
| Cube | 58505966061661 |
| Square root | 197.030454 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 181 |
| Scientific notation | 3.8821 × |
38821 in other forms
| Form | Value |
|---|---|
| In words | thirty-eight thousand eight hundred and twenty-one |
| Binary (base 2) | 1001011110100101 |
| Octal (base 8) | 113645 |
| Hexadecimal (base 16) | 97A5 |
| Base 3 | 1222020211 |
| As time | 38821 seconds = 10 h 47 min 1 s |
Is 38821 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 1) | 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 1) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 6) | 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 4) | 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 2) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 38821 a prime number?
Yes. 38821 is divisible only by 1 and itself.
What are the factors of 38821?
1, 38821.
What is 38821 in binary?
1001011110100101 (hexadecimal 97A5, octal 113645).
What is the square root of 38821?
About 197.0305.
Is 38821 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 38821?
38821 is the 4090th prime number.