The number 21407
21407 is the 2404th prime number. Its only divisors are 1 and 21407.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 21407: the 2404th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
21407 is prime, so its only factors are 1 and 21407. It is the 2404th prime; the next prime is 21419 and the one before is 21401.
- 3
The divisors add up to 21408; without 21407 itself that is 1, so 21407 is deficient (1 is less than 21407). Euler's totient φ(21407) = 21406 numbers up to 21407 share no factor with it.
- 4
The digits of 21407 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 193 steps to reach 1.
21407 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 21408 |
| Euler totient φ(n) | 21406 |
| Square | 458259649 |
| Cube | 9809964306143 |
| Square root | 146.311312 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 193 |
| Scientific notation | 2.1407 × |
21407 in other forms
| Form | Value |
|---|---|
| In words | twenty-one thousand four hundred and seven |
| Binary (base 2) | 101001110011111 |
| Octal (base 8) | 51637 |
| Hexadecimal (base 16) | 539F |
| Base 3 | 1002100212 |
| As time | 21407 seconds = 5 h 56 min 47 s |
Is 21407 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 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 2) | 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 7) | 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 7) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 21407 a prime number?
Yes. 21407 is divisible only by 1 and itself.
What are the factors of 21407?
1, 21407.
What is 21407 in binary?
101001110011111 (hexadecimal 539F, octal 51637).
What is the square root of 21407?
About 146.3113.
Is 21407 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 21407?
21407 is the 2404th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.