978

978 is a natural number that follows 977 and precedes 979. It is an even, composite number with prime factorization 2 × 3 × 163, and is squarefree. The positive divisors are 1, 2, 3, 6, 163, 326, 489, and 978, giving it eight divisors.

In decimal notation it is 978. In binary it is 1111010010 and in hexadecimal it is 0x3D2. In Roman numerals it is CMLXXVIII.

978 has practical uses in naming and coding systems. It is an area code in the United States covering parts of central Massachusetts, including Worcester and surrounding communities. In publishing and library contexts, 978 is one of the International Standard Book Number (ISBN) prefixes used to identify books in the ISBN-13 system; the other prefix, 979, is reserved for different uses.

From a historical perspective, the year 978 CE falls in the late tenth century. As a number, 978 is often cited as an example of a small, squarefree composite number in mathematical discussions.