427

427 is a natural number that follows 426 and precedes 428. In number theory, it is a semiprime, since it factors into two primes: 7 and 61. Its prime factorization is 7 × 61, making it an odd composite. The Euler totient of 427 is φ(427) = (7 − 1)(61 − 1) = 360.

In arithmetic terms, 427 is congruent to 3 modulo 4 (427 ≡ 3 (mod 4)). It is not divisible by small primes such as 2, 3, or 5. In different bases, 427 is represented as 110101011 in binary and 0x1AB in hexadecimal.

In Roman numerals, 427 is written as CDXXVII.

Historically, 427 may denote a year in either the Common Era (CE) or Before Common Era (BCE). Years labeled 427 CE or 427 BCE appear in chronologies of various historical civilizations, though specific events depend on regional histories.

In science and measurement, 427 nanometers lies in the violet portion of the visible spectrum. Wavelengths around this value are used in spectroscopy and certain lighting and display technologies.

Beyond these uses, 427 appears in various cataloging systems, model numbers, and route or designation codes. Such applications depend on the country, organization, or context in which the number is employed.