The number 42721
42721 is a composite number with 8 divisors. Its prime factorisation is 7 × 17 × 359. Divisors (8): 1, 7, 17, 119, 359, 2513, 6103, 42721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
42721 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
42721 is composite. Its prime factorisation is
- 3
The divisors add up to 51840; without 42721 itself that is 9119, so 42721 is deficient (9119 is less than 42721). Euler's totient φ(42721) = 34368 numbers up to 42721 share no factor with it.
- 4
The digits of 42721 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 101 steps to reach 1.
LaTeX source of the formulas on this page
\[ 42721 = 7 \times 17 \times 359 \]
42721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 51840 |
| Euler totient φ(n) | 34368 |
| Square | 1825083841 |
| Cube | 77969406771361 |
| Square root | 206.690590 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 101 |
| Scientific notation | 4.2721 × |
42721 in other forms
| Form | Value |
|---|---|
| In words | forty-two thousand seven hundred and twenty-one |
| Binary (base 2) | 1010011011100001 |
| Octal (base 8) | 123341 |
| Hexadecimal (base 16) | A6E1 |
| Base 3 | 2011121021 |
| As time | 42721 seconds = 11 h 52 min 1 s |
Is 42721 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 | Yes (42721 ÷ 7 = 6103) | 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 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 8) | 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 42721 a prime number?
No. 42721 = 7 × 17 × 359, so it is divisible by 7.
What are the factors of 42721?
1, 7, 17, 119, 359, 2513, 6103, 42721.
What is 42721 in binary?
1010011011100001 (hexadecimal A6E1, octal 123341).
What is the square root of 42721?
About 206.6906.
Is 42721 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 42721?
It is a composite number with 8 divisors.