The number 40821
40821 is a composite number with 8 divisors. Its prime factorisation is 3 × 11 × 1237. Divisors (8): 1, 3, 11, 33, 1237, 3711, 13607, 40821.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
40821 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
40821 is composite. Its prime factorisation is
- 3
The divisors add up to 59424; without 40821 itself that is 18603, so 40821 is deficient (18603 is less than 40821). Euler's totient φ(40821) = 24720 numbers up to 40821 share no factor with it.
- 4
The digits of 40821 add up to 15, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 88 steps to reach 1.
LaTeX source of the formulas on this page
\[ 40821 = 3 \times 11 \times 1237 \]
40821 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 59424 |
| Euler totient φ(n) | 24720 |
| Square | 1666354041 |
| Cube | 68022238307661 |
| Square root | 202.042075 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 88 |
| Scientific notation | 4.0821 × |
40821 in other forms
| Form | Value |
|---|---|
| In words | forty thousand eight hundred and twenty-one |
| Binary (base 2) | 1001111101110101 |
| Octal (base 8) | 117565 |
| Hexadecimal (base 16) | 9F75 |
| Base 3 | 2001222220 |
| As time | 40821 seconds = 11 h 20 min 21 s |
Is 40821 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 (40821 ÷ 3 = 13607) | 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 4) | 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 6) | 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 | Yes (40821 ÷ 11 = 3711) | 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 40821 a prime number?
No. 40821 = 3 × 11 × 1237, so it is divisible by 3.
What are the factors of 40821?
1, 3, 11, 33, 1237, 3711, 13607, 40821.
What is 40821 in binary?
1001111101110101 (hexadecimal 9F75, octal 117565).
What is the square root of 40821?
About 202.0421.
Is 40821 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 40821?
It is a composite number with 8 divisors.