The number 16391
16391 is a composite number with 4 divisors. Its prime factorisation is 37 × 443. Divisors (4): 1, 37, 443, 16391.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 16391: a semiprime: 37 × 443, the product of two primes.
- 2
16391 is composite. Its prime factorisation is
- 3
The divisors add up to 16872; without 16391 itself that is 481, so 16391 is deficient (481 is less than 16391). Euler's totient φ(16391) = 15912 numbers up to 16391 share no factor with it.
- 4
The digits of 16391 add up to 20, and repeating that until one digit is left gives the digital root 2. The Collatz sequence (halve if even, else 3n+1) takes 53 steps to reach 1.
LaTeX source of the formulas on this page
\[ 16391 = 37 \times 443 \]
16391 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 16872 |
| Euler totient φ(n) | 15912 |
| Square | 268664881 |
| Cube | 4403686064471 |
| Square root | 128.027341 |
| Digit sum / digital root | 20 / 2 |
| Collatz steps to 1 | 53 |
| Scientific notation | 1.6391 × |
16391 in other forms
| Form | Value |
|---|---|
| In words | sixteen thousand three hundred and ninety-one |
| Binary (base 2) | 100000000000111 |
| Octal (base 8) | 40007 |
| Hexadecimal (base 16) | 4007 |
| Base 3 | 211111002 |
| As time | 16391 seconds = 4 h 33 min 11 s |
Is 16391 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 2) | 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 | No (remainder 1) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 5) | 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 | No (remainder 2) | 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 1) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 11) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 16391 a prime number?
No. 16391 = 37 × 443, so it is divisible by 37.
What are the factors of 16391?
1, 37, 443, 16391.
What is 16391 in binary?
100000000000111 (hexadecimal 4007, octal 40007).
What is the square root of 16391?
About 128.0273.
Is 16391 divisible by 3?
No. Its digits add up to 20, which is not a multiple of 3.
What is special about the number 16391?
16391 is a semiprime: 37 × 443, the product of two primes.