886 is a natural number following 885 and preceding 887. It can also refer to the calendar year 886 in the Common Era (AD), a year marked by several notable events in early medieval Europe.

Mathematical properties

  • Classification: 886 is an even composite number and a semiprime, since it is the product of two prime numbers.
  • Prime factorization: 886 = 2 × 443, with 443 itself prime. Because 443 is a Sophie Germain prime (2·443 + 1 = 887, which is prime), 886 is twice a Sophie Germain prime.
  • Divisors: 1, 2, 443, 886. The sum of the proper divisors is 1 + 2 + 443 = 446, which is less than 886, so 886 is a deficient number.
  • Representations:
    • Binary: 1101110110
    • Octal: 1566
    • Hexadecimal: 0x376
    • Roman numerals: DCCCLXXXVI
  • Digit sum: 8 + 8 + 6 = 22.

Year 886 (AD)

The year 886 (DCCCLXXXVI) falls in the late Carolingian period in Western Europe and in the later portion of the Tang era in East Asia. Surviving chronicles and annals record several military and political developments; the following items summarize widely cited events while avoiding over-specific claims where contemporary sources disagree.

Europe

  • Siege of Paris (885–886): The Viking siege that began in 885 concluded in 886. Contemporary accounts indicate the besiegers eventually withdrew after negotiations and payments; the episode reinforced the importance of fortified towns and raised the reputation of local leaders who organized the city's defense.
  • Alfred the Great and London: King Alfred of Wessex reasserted control over London and ordered repairs and strengthening of its fortifications. He established a fortified borough (a burh) within the older Roman walls to improve defenses against further Viking raids and to encourage settled trade and governance.
  • Carolingian politics: The late 880s saw continued strain within the Carolingian realms. The emperor's efforts to manage Viking incursions and competing noble interests contributed to political fragmentation that would become more pronounced in subsequent years.

Other regions

  • In the Islamic world, local and regional rulers continued to govern under the framework of the Abbasid caliphate in the east and various independent dynasties elsewhere; military and political activity was locally significant but varied by region.
  • East Asia and other areas experienced their own regional developments in 886, but chronicling for many regions is uneven and subject to differing local sources.

Notes on historical sources

Chronicles from the late ninth century are often composed decades after the events they describe and may present differing versions of the same incident. Where precise dates or details are uncertain, historians rely on cross-checking annals, charters, archaeological evidence and later historiography to form a cautious consensus.