1142

1142 is a natural number that comes after 1141 and before 1143. It is an even composite number whose prime factorization is 2 × 571, with 571 being prime. Consequently, 1142 is a semiprime. Its divisors are 1, 2, 571, and 1142. In decimal it is written as 1142; in binary it is 10001110110, in octal it is 2166, and in hexadecimal it is 0x476. In Roman numerals, 1142 is MCXLII.

In calendar terms, 1142 refers to the year AD 1142 in the Julian calendar. It was a common year. The year sits in the broader context of the High Middle Ages, a period marked by feudal monarchies, the growth of towns and scholastic centers, and the ongoing Crusades in Europe and the Levant. Across different regions, historical records from the era reflect the political, cultural, and religious currents of medieval society.

From a mathematical perspective, 1142 has several notable properties. It is an even, composite number and, as mentioned, a semiprime. The Euler totient function yields φ(1142) = 570, since 1142 = 2 × 571 with 2 and 571 prime. Its representations in common bases (binary, octal, hexadecimal) and its Roman numeral form (MCXLII) illustrate how this number appears across numeral systems used in mathematics and history.