18446744073709551616

18446744073709551616 is the decimal representation of 2^64, a fundamental power of two in computer science. It is the smallest integer greater than the maximum value representable by an unsigned 64-bit integer, which is 18446744073709551615 (2^64 − 1). In binary, 2^64 equals a 1 followed by 64 zeros, and in hexadecimal it is 0x10000000000000000. The value is also the size of the 64-bit unsigned integer space: there are 2^64 distinct values that can be stored, from 0 to 2^64 − 1.

In modular arithmetic with modulus 2^64, the equivalence class of 2^64 is 0. This property underlies wraparound behavior in many programming languages when performing unsigned 64-bit arithmetic; for example, adding 1 to 2^64 − 1 yields 0.

The concept is central in discussions of 64-bit architecture and memory addressing. If a system uses one-byte addressing, the theoretical maximum addressable memory is 2^64 bytes, equal to 16 exbibytes. Practically, hardware and software often constrain usable address space, but 2^64 defines the theoretical bound.

Because of its role as a modulus and boundary, 2^64 appears in algorithm design, cryptography, and tests for overflow or boundary conditions. 18446744073709551616 serves as a numerical reference for these contexts.