512

512 is the natural number that follows 511 and precedes 513. In mathematical terms, it is the ninth power of two, 2^9. In binary, 512 is written as 1000000000, a 1 followed by nine zeros. Its prime factorization is 2^9, so its only prime factor is 2. It is an even composite number.

In computing and data storage, 512 is notable as a standard block size. A 512-byte sector or block was a common unit of data on many older hard drives, optical disks, and memory devices. Because 512 = 2^9, it is a power of two, a property that simplifies addressing and alignment in hardware. Modern storage sometimes uses 4,096-byte sectors (4 KiB) but can still present logical 512-byte blocks through sector size emulation (512e).

In digital addressing, 512 distinct values can be represented with 9 bits, since 2^9 = 512. This makes 512 a natural boundary in certain low-level systems and historical computer architectures.

Other uses include the area code 512 for parts of Texas, notably the Austin metropolitan area. The number also appears in various cultural and historical references as a numeral without universal significance.