810

810 is a natural number that follows 809 and precedes 811. In mathematics, it is an even, composite integer with several notable properties. Its prime factorization is 2 × 3^4 × 5, and it has 20 positive divisors. The sum of its proper divisors is 1,368, so 810 is an abundant number. The digits sum to 9, and since 810 is divisible by 9, it is also a Harshad (Niven) number in base 10. In Roman numerals it is written as DCCCX, and in binary it is 1100101010 because 512 + 256 + 32 + 8 + 2 equals 810.

810 also denotes the year AD 810 in the Julian calendar, a point in the early Middle Ages when various kingdoms and empires maintained frontiers across Europe and Asia.

In modern contexts, 810 is used as an area code in Michigan for parts of the state within the North American Numbering Plan.