The number 15729
15729 is a composite number with 12 divisors. Its prime factorisation is 3 × × 107. Divisors (12): 1, 3, 7, 21, 49, 107, 147, 321, 749, 2247, 5243, 15729.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
15729 has no famous special property in the usual lists (prime, square, cube, triangular, Fibonacci, palindrome, perfect), but it is still a composite number.
- 2
15729 is composite. Its prime factorisation is
- 3
The divisors add up to 24624; without 15729 itself that is 8895, so 15729 is deficient (8895 is less than 15729). Euler's totient φ(15729) = 8904 numbers up to 15729 share no factor with it.
- 4
The digits of 15729 add up to 24, and repeating that until one digit is left gives the digital root 6. The Collatz sequence (halve if even, else 3n+1) takes 146 steps to reach 1.
LaTeX source of the formulas on this page
\[ 15729 = 3 \times 7^{2} \times 107 \]15729 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 24624 |
| Euler totient φ(n) | 8904 |
| Square | 247401441 |
| Cube | 3891377265489 |
| Square root | 125.415310 (= 7√321) |
| Digit sum / digital root | 24 / 6 |
| Collatz steps to 1 | 146 |
| Scientific notation | 1.5729 × |
15729 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand seven hundred and twenty-nine |
| Binary (base 2) | 11110101110001 |
| Octal (base 8) | 36561 |
| Hexadecimal (base 16) | 3D71 |
| Base 3 | 210120120 |
| As time | 15729 seconds = 4 h 22 min 9 s |
Is 15729 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 (15729 ÷ 3 = 5243) | 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 4) | 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 | Yes (15729 ÷ 7 = 2247) | 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 9) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 15729 a prime number?
No. 15729 = 3 × × 107, so it is divisible by 3.
What are the factors of 15729?
1, 3, 7, 21, 49, 107, 147, 321, 749, 2247, 5243, 15729.
What is 15729 in binary?
11110101110001 (hexadecimal 3D71, octal 36561).
What is the square root of 15729?
About 125.4153, exactly 7√321.
Is 15729 divisible by 3?
Yes. Its digits add up to 24, a multiple of 3.
What is special about the number 15729?
It is a composite number with 12 divisors.