The number 13815
13815 is a composite number with 12 divisors. Its prime factorisation is × 5 × 307. Divisors (12): 1, 3, 5, 9, 15, 45, 307, 921, 1535, 2763, 4605, 13815.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 13815: a happy number: repeatedly adding the squares of its digits reaches 1.
- 2
13815 is composite. Its prime factorisation is
- 3
The divisors add up to 24024; without 13815 itself that is 10209, so 13815 is deficient (10209 is less than 13815). Euler's totient φ(13815) = 7344 numbers up to 13815 share no factor with it.
- 4
The digits of 13815 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 120 steps to reach 1.
LaTeX source of the formulas on this page
\[ 13815 = 3^{2} \times 5 \times 307 \]13815 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 12 |
| Sum of divisors | 24024 |
| Euler totient φ(n) | 7344 |
| Square | 190854225 |
| Cube | 2636651118375 |
| Square root | 117.537228 (= 3√1535) |
| Digit sum / digital root | 18 / 9 |
| Collatz steps to 1 | 120 |
| Scientific notation | 1.3815 × |
13815 in other forms
| Form | Value |
|---|---|
| In words | thirteen thousand eight hundred and fifteen |
| Binary (base 2) | 11010111110111 |
| Octal (base 8) | 32767 |
| Hexadecimal (base 16) | 35F7 |
| Base 3 | 200221200 |
| As time | 13815 seconds = 3 h 50 min 15 s |
Is 13815 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 (13815 ÷ 3 = 4605) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 3) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | Yes (13815 ÷ 5 = 2763) | 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 4) | 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 7) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | Yes (13815 ÷ 9 = 1535) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 5) | 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 3) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 13815 a prime number?
No. 13815 = × 5 × 307, so it is divisible by 3.
What are the factors of 13815?
1, 3, 5, 9, 15, 45, 307, 921, 1535, 2763, 4605, 13815.
What is 13815 in binary?
11010111110111 (hexadecimal 35F7, octal 32767).
What is the square root of 13815?
About 117.5372, exactly 3√1535.
Is 13815 divisible by 3?
Yes. Its digits add up to 18, a multiple of 3.
What is special about the number 13815?
13815 is a happy number: repeatedly adding the squares of its digits reaches 1.