The number 13881
13881 is a composite number with 8 divisors. Its prime factorisation is 3 × 7 × 661. Divisors (8): 1, 3, 7, 21, 661, 1983, 4627, 13881.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 13881: a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 21.
- 2
13881 is composite. Its prime factorisation is
- 3
The divisors add up to 21184; without 13881 itself that is 7303, so 13881 is deficient (7303 is less than 13881). Euler's totient φ(13881) = 7920 numbers up to 13881 share no factor with it.
- 4
The digits of 13881 add up to 21, and repeating that until one digit is left gives the digital root 3. The Collatz sequence (halve if even, else 3n+1) takes 151 steps to reach 1.
LaTeX source of the formulas on this page
\[ 13881 = 3 \times 7 \times 661 \]
13881 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 8 |
| Sum of divisors | 21184 |
| Euler totient φ(n) | 7920 |
| Square | 192682161 |
| Cube | 2674621076841 |
| Square root | 117.817656 |
| Digit sum / digital root | 21 / 3 |
| Collatz steps to 1 | 151 |
| Scientific notation | 1.3881 × |
13881 in other forms
| Form | Value |
|---|---|
| In words | thirteen thousand eight hundred and eighty-one |
| Binary (base 2) | 11011000111001 |
| Octal (base 8) | 33071 |
| Hexadecimal (base 16) | 3639 |
| Base 3 | 201001010 |
| As time | 13881 seconds = 3 h 51 min 21 s |
Is 13881 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 (13881 ÷ 3 = 4627) | 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 | Yes (13881 ÷ 7 = 1983) | 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 3) | 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 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 13881 a prime number?
No. 13881 = 3 × 7 × 661, so it is divisible by 3.
What are the factors of 13881?
1, 3, 7, 21, 661, 1983, 4627, 13881.
What is 13881 in binary?
11011000111001 (hexadecimal 3639, octal 33071).
What is the square root of 13881?
About 117.8177.
Is 13881 divisible by 3?
Yes. Its digits add up to 21, a multiple of 3.
What is special about the number 13881?
13881 is a happy number: repeatedly adding the squares of its digits reaches 1; a Harshad number: divisible by its digit sum 21.