178

178 is a natural number that follows 177 and precedes 179. In mathematics, it is even and composite, with prime factorization 178 = 2 × 89. Its divisors are 1, 2, 89, and 178, making it a semiprime (the product of two primes).

In various numeral systems, 178 has representations that are often used for illustration. In Roman numerals it is CLXXVIII. In binary it is 10110010, in hexadecimal it is B2, and in octal it is 262. The sum of its decimal digits is 16, and it is not divisible by 3 or 5.

As a number in number theory, 178 is notable primarily for being an even semiprime. It is not a prime, a square, or a cube, and it does not belong to simpler notable sequences beyond its basic factorization.

Historically, 178 can refer to calendar years in different eras, such as 178 AD or 178 BC, each associated with events in various civilizations—though such events depend on historical context and sources rather than properties of the number itself.

See also the general properties of semiprimes and the basic representations of integers in common bases, which illustrate how 178 appears across different mathematical systems.