The number 6421
6421 is the 835th prime number. Its only divisors are 1 and 6421.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 6421: the 835th prime number.
- 2
6421 is prime, so its only factors are 1 and 6421. It is the 835th prime; the next prime is 6427 and the one before is 6397.
- 3
The divisors add up to 6422; without 6421 itself that is 1, so 6421 is deficient (1 is less than 6421). Euler's totient φ(6421) = 6420 numbers up to 6421 share no factor with it.
- 4
The digits of 6421 add up to 13, and repeating that until one digit is left gives the digital root 4. The Collatz sequence (halve if even, else 3n+1) takes 23 steps to reach 1.
6421 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 6422 |
| Euler totient φ(n) | 6420 |
| Square | 41229241 |
| Cube | 264732956461 |
| Square root | 80.131143 |
| Digit sum / digital root | 13 / 4 |
| Collatz steps to 1 | 23 |
| Scientific notation | 6.421 × |
6421 in other forms
| Form | Value |
|---|---|
| In words | six thousand four hundred and twenty-one |
| Binary (base 2) | 1100100010101 |
| Octal (base 8) | 14425 |
| Hexadecimal (base 16) | 1915 |
| Base 3 | 22210211 |
| As time | 6421 seconds = 1 h 47 min 1 s |
Is 6421 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 2) | 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 8) | 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 6421 a prime number?
Yes. 6421 is divisible only by 1 and itself.
What are the factors of 6421?
1, 6421.
What is 6421 in binary?
1100100010101 (hexadecimal 1915, octal 14425).
What is the square root of 6421?
About 80.1311.
Is 6421 divisible by 3?
No. Its digits add up to 13, which is not a multiple of 3.
What is special about the number 6421?
6421 is the 835th prime number.