The number 43821
43821 is a composite number with 10 divisors. Its prime factorisation is × 541. Divisors (10): 1, 3, 9, 27, 81, 541, 1623, 4869, 14607, 43821.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 43821: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
43821 is composite. Its prime factorisation is
- 3
The divisors add up to 65582; without 43821 itself that is 21761, so 43821 is deficient (21761 is less than 43821). Euler's totient φ(43821) = 29160 numbers up to 43821 share no factor with it.
- 4
The digits of 43821 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 163 steps to reach 1.
LaTeX source of the formulas on this page
\[ 43821 = 3^{4} \times 541 \]43821 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 10 |
| Sum of divisors | 65582 |
| Euler totient φ(n) | 29160 |
| Square | 1920280041 |
| Cube | 84148591676661 |
| Square root | 209.334660 (= 9√541) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 163 |
| Scientific notation | 4.3821 × |
43821 in other forms
| Form | Value |
|---|---|
| In words | forty-three thousand eight hundred and twenty-one |
| Binary (base 2) | 1010101100101101 |
| Octal (base 8) | 125455 |
| Hexadecimal (base 16) | AB2D |
| Base 3 | 2020010000 |
| As time | 43821 seconds = 12 h 10 min 21 s |
Is 43821 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 | Yes (43821 ÷ 3 = 14607) | 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 3) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (43821 ÷ 9 = 4869) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 43821 a prime number?
No. 43821 = × 541, so it is divisible by 3.
What are the factors of 43821?
1, 3, 9, 27, 81, 541, 1623, 4869, 14607, 43821.
What is 43821 in binary?
1010101100101101 (hexadecimal AB2D, octal 125455).
What is the square root of 43821?
About 209.3347, exactly 9√541.
Is 43821 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 43821?
43821 is a happy number: repeatedly adding the squares of its digits reaches 1.