The number 21379
21379 is a twin prime (21377 and 21379 are both prime) and the 2399th prime number. Its only divisors are 1 and 21379.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21379: a twin prime (21377 and 21379 are both prime); the 2399th prime number.
- 2
21379 is prime, so its only factors are 1 and 21379. It is the 2399th prime; the next prime is 21383 and the one before is 21377.
- 3
The divisors add up to 21380; without 21379 itself that is 1, so 21379 is deficient (1 is less than 21379). Euler's totient φ(21379) = 21378 numbers up to 21379 share no factor with it.
- 4
The digits of 21379 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 149 steps to reach 1.
21379 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21380 |
| Euler totient φ(n) | 21378 |
| Square | 457061641 |
| Cube | 9771520822939 |
| Square root | 146.215594 |
| Digit sum / digital root | 22 / 4 |
| Collatz steps to 1 | 149 |
| Scientific notation | 2.1379 × |
21379 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand three hundred and seventy-nine |
| Binary (base 2) | 101001110000011 |
| Octal (base 8) | 51603 |
| Hexadecimal (base 16) | 5383 |
| Base 3 | 1002022211 |
| As time | 21379 seconds = 5 h 56 min 19 s |
Is 21379 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 4) | 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 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 3) | 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 9) | 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 7) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21379 a prime number?
Yes. 21379 is divisible only by 1 and itself.
What are the factors of 21379?
1, 21379.
What is 21379 in binary?
101001110000011 (hexadecimal 5383, octal 51603).
What is the square root of 21379?
About 146.2156.
Is 21379 divisible by 3?
No. Its digits add up to 22, which is not a multiple of 3.
What is special about the number 21379?
21379 is a twin prime (21377 and 21379 are both prime); the 2399th prime number.