The number 40021
40021 is a composite number with 4 divisors. Its prime factorisation is 31 × 1291. Divisors (4): 1, 31, 1291, 40021.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 40021: a semiprime: 31 × 1291, the product of two primes.
- 2
40021 is composite. Its prime factorisation is
- 3
The divisors add up to 41344; without 40021 itself that is 1323, so 40021 is deficient (1323 is less than 40021). Euler's totient φ(40021) = 38700 numbers up to 40021 share no factor with it.
- 4
The digits of 40021 add up to 7, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 31 steps to reach 1.
LaTeX source of the formulas on this page
\[ 40021 = 31 \times 1291 \]
40021 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 41344 |
| Euler totient φ(n) | 38700 |
| Square | 1601680441 |
| Cube | 64100852929261 |
| Square root | 200.052493 |
| Digit sum / digital root | 7 / 7 |
| Collatz steps to 1 | 31 |
| Scientific notation | 4.0021 × |
40021 in other forms
| Form | Value |
|---|---|
| In words | forty thousand and twenty-one |
| Binary (base 2) | 1001110001010101 |
| Octal (base 8) | 116125 |
| Hexadecimal (base 16) | 9C55 |
| Base 3 | 2000220021 |
| As time | 40021 seconds = 11 h 7 min 1 s |
Is 40021 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 1) | 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 1) | 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 5) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 3) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 40021 a prime number?
No. 40021 = 31 × 1291, so it is divisible by 31.
What are the factors of 40021?
1, 31, 1291, 40021.
What is 40021 in binary?
1001110001010101 (hexadecimal 9C55, octal 116125).
What is the square root of 40021?
About 200.0525.
Is 40021 divisible by 3?
No. Its digits add up to 7, which is not a multiple of 3.
What is special about the number 40021?
40021 is a semiprime: 31 × 1291, the product of two primes.