The number 13561
13561 is a composite number with 4 divisors. Its prime factorisation is 71 × 191. Divisors (4): 1, 71, 191, 13561.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 13561: a semiprime: 71 × 191, the product of two primes.
- 2
13561 is composite. Its prime factorisation is
- 3
The divisors add up to 13824; without 13561 itself that is 263, so 13561 is deficient (263 is less than 13561). Euler's totient φ(13561) = 13300 numbers up to 13561 share no factor with it.
- 4
The digits of 13561 add up to 16, and repeating that until one digit is left gives the digital root 7. The Collatz sequence (halve if even, else 3n+1) takes 89 steps to reach 1.
LaTeX source of the formulas on this page
\[ 13561 = 71 \times 191 \]
13561 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 13824 |
| Euler totient φ(n) | 13300 |
| Square | 183900721 |
| Cube | 2493877677481 |
| Square root | 116.451707 |
| Digit sum / digital root | 16 / 7 |
| Collatz steps to 1 | 89 |
| Scientific notation | 1.3561 × |
13561 in other forms
| Form | Value |
|---|---|
| In words | thirteen thousand five hundred and sixty-one |
| Binary (base 2) | 11010011111001 |
| Octal (base 8) | 32371 |
| Hexadecimal (base 16) | 34F9 |
| Base 3 | 200121021 |
| As time | 13561 seconds = 3 h 46 min 1 s |
Is 13561 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 | No (remainder 1) | 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 1) | 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 1) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 7) | 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 9) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 1) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 13561 a prime number?
No. 13561 = 71 × 191, so it is divisible by 71.
What are the factors of 13561?
1, 71, 191, 13561.
What is 13561 in binary?
11010011111001 (hexadecimal 34F9, octal 32371).
What is the square root of 13561?
About 116.4517.
Is 13561 divisible by 3?
No. Its digits add up to 16, which is not a multiple of 3.
What is special about the number 13561?
13561 is a semiprime: 71 × 191, the product of two primes.