628

628 is a natural number that follows 627 and precedes 629. It is an even, composite number. Its prime factorization is 2^2 × 157, so its positive divisors are 1, 2, 4, 157, 314, and 628. It is not divisible by 3 or 5. The sum of its digits is 16, so it is not a multiple of 3 or 9. The square root is about 25.06, placing it near 25^2 = 625. In different bases, 628 is written as 1001110100 in binary, 1164 in octal, 0x274 in hexadecimal, and DCXXVIII in Roman numerals.

As a year, AD 628 (CE 628) is notable in late antiquity and early Islamic history. In the Byzantine–Sassanid War, the Sassanian emperor Khosrow II was overthrown and killed, with Kavadh II succeeding him. In the Arabian Peninsula, the Treaty of Hudaybiyya was signed between the Prophet Muhammad and the Quraysh of Mecca, establishing a ten-year truce and influencing the course of early Islamic relations. These events contributed to shifts in regional power and helped set the stage for subsequent developments in the region.

In summary, 628 is characterized mathematically by its factorization and representations across bases, and historically by its association with significant events in 628 CE, including leadership changes in Persia and the treaty between early Muslims and Mecca.