443

443 is a natural number that comes after 442 and before 444. In mathematics, 443 is prime, meaning it has exactly two distinct positive divisors: 1 and 443. It is odd and congruent to 3 modulo 4. As such, 443 cannot be expressed as a sum of two perfect squares. In binary, 443 is 110111011.

In Roman numerals, 443 is CDXLIII.

In computing, port 443 is the default port used by the HTTPS protocol for secure web traffic, operating over TCP. It typically carries TLS or SSL encryption and is essential for encrypted communication on the World Wide Web.

In telecommunications, 443 is an area code for parts of Maryland as an overlay for the Baltimore region under the North American Numbering Plan.