The number 23721
23721 is a composite number with 4 divisors. Its prime factorisation is 3 × 7907. Divisors (4): 1, 3, 7907, 23721.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 23721: a semiprime: 3 × 7907, the product of two primes.
- 2
23721 is composite. Its prime factorisation is
- 3
The divisors add up to 31632; without 23721 itself that is 7911, so 23721 is deficient (7911 is less than 23721). Euler's totient φ(23721) = 15812 numbers up to 23721 share no factor with it.
- 4
The digits of 23721 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 74 steps to reach 1.
LaTeX source of the formulas on this page
\[ 23721 = 3 \times 7907 \]
23721 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 31632 |
| Euler totient φ(n) | 15812 |
| Square | 562685841 |
| Cube | 13347470834361 |
| Square root | 154.016233 |
| Digit sum / digital root | 15 / 6 |
| Collatz steps to 1 | 74 |
| Scientific notation | 2.3721 × |
23721 in other forms
| Form | Value |
|---|---|
| In words | twenty-three thousand seven hundred and twenty-one |
| Binary (base 2) | 101110010101001 |
| Octal (base 8) | 56251 |
| Hexadecimal (base 16) | 5CA9 |
| Base 3 | 1012112120 |
| As time | 23721 seconds = 6 h 35 min 21 s |
Is 23721 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 (23721 ÷ 3 = 7907) | 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 5) | 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 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 | No (remainder 5) | 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 23721 a prime number?
No. 23721 = 3 × 7907, so it is divisible by 3.
What are the factors of 23721?
1, 3, 7907, 23721.
What is 23721 in binary?
101110010101001 (hexadecimal 5CA9, octal 56251).
What is the square root of 23721?
About 154.0162.
Is 23721 divisible by 3?
Yes. Its digits add up to 15, a multiple of 3.
What is special about the number 23721?
23721 is a semiprime: 3 × 7907, the product of two primes.