The number 15381
15381 is a composite number with 6 divisors. Its prime factorisation is × 1709. Divisors (6): 1, 3, 9, 1709, 5127, 15381.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 15381: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
15381 is composite. Its prime factorisation is
- 3
The divisors add up to 22230; without 15381 itself that is 6849, so 15381 is deficient (6849 is less than 15381). Euler's totient φ(15381) = 10248 numbers up to 15381 share no factor with it.
- 4
The digits of 15381 add up to 18, and repeating that until one digit is left gives the digital root 9. The Collatz sequence (halve if even, else 3n+1) takes 53 steps to reach 1.
LaTeX source of the formulas on this page
\[ 15381 = 3^{2} \times 1709 \]15381 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 6 |
| Sum of divisors | 22230 |
| Euler totient φ(n) | 10248 |
| Square | 236575161 |
| Cube | 3638762551341 |
| Square root | 124.020160 (= 3√1709) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 53 |
| Scientific notation | 1.5381 × |
15381 in other forms
| Form | Value |
|---|---|
| In words | fifteen thousand three hundred and eighty-one |
| Binary (base 2) | 11110000010101 |
| Octal (base 8) | 36025 |
| Hexadecimal (base 16) | 3C15 |
| Base 3 | 210002200 |
| As time | 15381 seconds = 4 h 16 min 21 s |
Is 15381 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 (15381 ÷ 3 = 5127) | 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 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 | Yes (15381 ÷ 9 = 1709) | 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 9) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 15381 a prime number?
No. 15381 = × 1709, so it is divisible by 3.
What are the factors of 15381?
1, 3, 9, 1709, 5127, 15381.
What is 15381 in binary?
11110000010101 (hexadecimal 3C15, octal 36025).
What is the square root of 15381?
About 124.0202, exactly 3√1709.
Is 15381 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 15381?
15381 is a happy number: repeatedly adding the squares of its digits reaches 1.