The number 43721
43721 is the 4555th prime number. Its only divisors are 1 and 43721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 43721: the 4555th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
43721 is prime, so its only factors are 1 and 43721. It is the 4555th prime; the next prime is 43753 and the one before is 43717.
- 3
The divisors add up to 43722; without 43721 itself that is 1, so 43721 is deficient (1 is less than 43721). Euler's totient φ(43721) = 43720 numbers up to 43721 share no factor with it.
- 4
The digits of 43721 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 119 steps to reach 1.
43721 at a glance
| Property | Value |
|---|---|
| Type | prime |
| Number of divisors | 2 |
| Sum of divisors | 43722 |
| Euler totient φ(n) | 43720 |
| Square | 1911525841 |
| Cube | 83573821294361 |
| Square root | 209.095672 |
| Digit sum / digital root | 17 / 8 |
| Collatz steps to 1 | 119 |
| Scientific notation | 4.3721 × |
43721 in other forms
| Form | Value |
|---|---|
| In words | forty-three thousand seven hundred and twenty-one |
| Binary (base 2) | 1010101011001001 |
| Octal (base 8) | 125311 |
| Hexadecimal (base 16) | AAC9 |
| Base 3 | 2012222022 |
| As time | 43721 seconds = 12 h 8 min 41 s |
Is 43721 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 6) | 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 7) | 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 43721 a prime number?
Yes. 43721 is divisible only by 1 and itself.
What are the factors of 43721?
1, 43721.
What is 43721 in binary?
1010101011001001 (hexadecimal AAC9, octal 125311).
What is the square root of 43721?
About 209.0957.
Is 43721 divisible by 3?
No. Its digits add up to 17, which is not a multiple of 3.
What is special about the number 43721?
43721 is the 4555th prime number; a happy number: repeatedly adding the squares of its digits reaches 1.