431

431 is a natural number that follows 430 and precedes 432. In mathematics, it is a prime number, meaning its only positive divisors are 1 and itself. It is odd and not divisible by any prime up to its square root (approximately 20). In base-10, the digits sum to 8. It can be written in binary as 110101111 and in hexadecimal as 0x1AF. In Roman numerals, 431 is written as CDXXXI.

Historically, the year 431 CE is notable for the Council of Ephesus, the third ecumenical council of the Christian church. The council addressed the Nestorian controversy and affirmed the title Theotokos for Mary, shaping theological and ecclesiastical developments in late antiquity.

In computing and networking, the decimal 431 appears as an HTTP status code: 431 Request Header Fields Too Large. This code is defined in RFC 6585 and is returned when a server refuses a request because its header fields are too large to process.

In telecommunications, area code 431 is used in Manitoba, Canada, as an overlay for the existing 204 region. The overlay approach allows continued assignment of new numbers without changing existing ones and reflects the region’s growing need for telephone numbers.