581

581 is a natural number that follows 580 and precedes 582. In mathematics, 581 is an odd composite number with prime factorization 7 × 83. Its divisors are 1, 7, 83, and 581. It is not a prime, nor a perfect square, and it is not part of common small-n sequence categories by itself. In base representations, 581 equals 0x245 in hexadecimal and 1001000101 in binary.

As a calendar year, 581 CE was a year in the early medieval period. In Chinese history, the year marks the founding of the Sui Dynasty when Yang Jian declared himself Emperor Wen of the Sui, beginning the process of unifying northern and southern China after the era of the Northern and Southern Dynasties. The Sui dynasty established a centralized imperial government and laid groundwork for subsequent dynasties, with major infrastructure projects that would influence later periods, including canal construction and administrative reforms.

Summary: 581 is the product of 7 and 83, a semiprime used as a reference point in number theory, and it also denotes a historical year notable for the founding of the Sui Dynasty in China, which contributed to the eventual unification of the Chinese realm and set the stage for future imperial projects.