The number 40721
40721 is a composite number with 4 divisors. Its prime factorisation is 43 × 947. Divisors (4): 1, 43, 947, 40721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 40721: a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 43 × 947, the product of two primes.
- 2
40721 is composite. Its prime factorisation is
- 3
The divisors add up to 41712; without 40721 itself that is 991, so 40721 is deficient (991 is less than 40721). Euler's totient φ(40721) = 39732 numbers up to 40721 share no factor with it.
- 4
The digits of 40721 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 88 steps to reach 1.
LaTeX source of the formulas on this page
\[ 40721 = 43 \times 947 \]
40721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 41712 |
| Euler totient φ(n) | 39732 |
| Square | 1658199841 |
| Cube | 67523555725361 |
| Square root | 201.794450 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 88 |
| Scientific notation | 4.0721 × |
40721 in other forms
| Form | Value |
|---|---|
| In words | forty thousand seven hundred and twenty-one |
| Binary (base 2) | 1001111100010001 |
| Octal (base 8) | 117421 |
| Hexadecimal (base 16) | 9F11 |
| Base 3 | 2001212012 |
| As time | 40721 seconds = 11 h 18 min 41 s |
Is 40721 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 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 1) | 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 1) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 10) | 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 40721 a prime number?
No. 40721 = 43 × 947, so it is divisible by 43.
What are the factors of 40721?
1, 43, 947, 40721.
What is 40721 in binary?
1001111100010001 (hexadecimal 9F11, octal 117421).
What is the square root of 40721?
About 201.7944.
Is 40721 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 40721?
40721 is a happy number: repeatedly adding the squares of its digits reaches 1; a semiprime: 43 × 947, the product of two primes.