The number 21401
21401 is the 2403rd prime number. Its only divisors are 1 and 21401.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21401: the 2403rd prime number.
- 2
21401 is prime, so its only factors are 1 and 21401. It is the 2403rd prime; the next prime is 21407 and the one before is 21397.
- 3
The divisors add up to 21402; without 21401 itself that is 1, so 21401 is deficient (1 is less than 21401). Euler's totient φ(21401) = 21400 numbers up to 21401 share no factor with it.
- 4
The digits of 21401 add up to 8, and repeating that until one digit is left gives the digital root 8. The Collatz sequence (halve if even, else 3n+1) takes 48 steps to reach 1.
21401 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21402 |
| Euler totient φ(n) | 21400 |
| Square | 458002801 |
| Cube | 9801717944201 |
| Square root | 146.290806 |
| Digit sum / digital root | 8 / 8 |
| Collatz steps to 1 | 48 |
| Scientific notation | 2.1401 × |
21401 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and one |
| Binary (base 2) | 101001110011001 |
| Octal (base 8) | 51631 |
| Hexadecimal (base 16) | 5399 |
| Base 3 | 1002100122 |
| As time | 21401 seconds = 5 h 56 min 41 s |
Is 21401 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 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 1) | 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 21401 a prime number?
Yes. 21401 is divisible only by 1 and itself.
What are the factors of 21401?
1, 21401.
What is 21401 in binary?
101001110011001 (hexadecimal 5399, octal 51631).
What is the square root of 21401?
About 146.2908.
Is 21401 divisible by 3?
No. Its digits add up to 8, which is not a multiple of 3.
What is special about the number 21401?
21401 is the 2403rd prime number.