The number 38921
38921 is a twin prime (38921 and 38923 are both prime) and the 4100th prime number. Its only divisors are 1 and 38921.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 38921: a twin prime (38921 and 38923 are both prime); the 4100th prime number.
- 2
38921 is prime, so its only factors are 1 and 38921. It is the 4100th prime; the next prime is 38923 and the one before is 38917.
- 3
The divisors add up to 38922; without 38921 itself that is 1, so 38921 is deficient (1 is less than 38921). Euler's totient φ(38921) = 38920 numbers up to 38921 share no factor with it.
- 4
The digits of 38921 add up to 23, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 106 steps to reach 1.
38921 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 38922 |
| Euler totient φ(n) | 38920 |
| Square | 1514844241 |
| Cube | 58959252703961 |
| Square root | 197.284059 |
| Digit sum / digital root | 23 / 5 |
| Collatz steps to 1 | 106 |
| Scientific notation | 3.8921 × |
38921 in other forms
| Form | Value |
|---|---|
| In words | thirty-eight thousand nine hundred and twenty-one |
| Binary (base 2) | 1001100000001001 |
| Octal (base 8) | 114011 |
| Hexadecimal (base 16) | 9809 |
| Base 3 | 1222101112 |
| As time | 38921 seconds = 10 h 48 min 41 s |
Is 38921 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 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 5) | 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 5) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 38921 a prime number?
Yes. 38921 is divisible only by 1 and itself.
What are the factors of 38921?
1, 38921.
What is 38921 in binary?
1001100000001001 (hexadecimal 9809, octal 114011).
What is the square root of 38921?
About 197.2841.
Is 38921 divisible by 3?
No. Its digits add up to 23, which is not a multiple of 3.
What is special about the number 38921?
38921 is a twin prime (38921 and 38923 are both prime); the 4100th prime number.