878

878 is the natural number that comes after 877 and before 879. It is an even composite number with prime factorization 2 × 439, and its positive divisors are 1, 2, 439, and 878. In Roman numerals, 878 is written as DCCCLXXVIII.

In mathematics, 878 is not a prime number. It can appear in various numerical patterns and has the divisors listed above. Its digit sum is 23, a prime number, a property sometimes noted in digit-sum explorations, though it does not confer any particular mathematical significance on the number itself.

Historically, the year 878 CE was notable in the context of the Viking Age and the early history of England. After the Battle of Edington in 878, Alfred the Great of Wessex defeated Guthrum’s Viking forces and secured a peace. This led to the creation of the so-called Danelaw, a region of England under Danish control, and is often associated with Guthrum’s baptism. The exact terms of the ensuing settlement are not fully known from contemporary sources, but the event is regarded as a turning point in resisting Viking incursions.

In modern usage, 878 is also an area code in the North American Numbering Plan, assigned to a portion of Pennsylvania. As with many numbers, 878 features in various identifiers and catalogues, but it has no single overarching significance beyond its numerical properties and historical associations.