278

278 is a natural number that comes after 277 and before 279. It is even and composite. Its prime factorization is 2 × 139, with 139 being a prime number. In Roman numerals it is written as CCLXXVIII.

In base representations, 278 is 100010110 in binary and 0x116 in hexadecimal.

In mathematical classification, 278 is a semiprime, since it is the product of exactly two primes (2 and 139). It is not a prime, not a perfect square, and not a triangular number.

As a calendar reference, 278 can denote the year 278 CE or 278 BCE, which are years in the ancient world; without accompanying events it is simply a point in a historical timeline.