The number 19421
19421 is a twin prime (19421 and 19423 are both prime) and the 2199th prime number. Its only divisors are 1 and 19421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 19421: a twin prime (19421 and 19423 are both prime); the 2199th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
19421 is prime, so its only factors are 1 and 19421. It is the 2199th prime; the next prime is 19423 and the one before is 19417.
- 3
The divisors add up to 19422; without 19421 itself that is 1, so 19421 is deficient (1 is less than 19421). Euler's totient φ(19421) = 19420 numbers up to 19421 share no factor with it.
- 4
The digits of 19421 add up to 17, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 123 steps to reach 1.
19421 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 19422 |
| Euler totient φ(n) | 19420 |
| Square | 377175241 |
| Cube | 7325120355461 |
| Square root | 139.359248 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 123 |
| Scientific notation | 1.9421 × |
19421 in other forms
| Form | Value |
|---|---|
| In words | nineteen thousand four hundred and twenty-one |
| Binary (base 2) | 100101111011101 |
| Octal (base 8) | 45735 |
| Hexadecimal (base 16) | 4BDD |
| Base 3 | 222122022 |
| As time | 19421 seconds = 5 h 23 min 41 s |
Is 19421 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 3) | 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 8) | 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 5) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 19421 a prime number?
Yes. 19421 is divisible only by 1 and itself.
What are the factors of 19421?
1, 19421.
What is 19421 in binary?
100101111011101 (hexadecimal 4BDD, octal 45735).
What is the square root of 19421?
About 139.3592.
Is 19421 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 19421?
19421 is a twin prime (19421 and 19423 are both prime); the 2199th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.