What is 2 63?

2^63 is a very large number, which is equal to 9,223,372,036,854,775,808. It is 2 raised to the power of 63.

This number is commonly used in computing and mathematics, as it is the maximum value that can be stored in a 64-bit integer.

To put it into perspective, if you had 2^63 grains of sand, you would have enough sand to fill the entire planet Earth, more than 1,000 times over.

2^63 also has some interesting properties, such as being exactly half of the maximum value that can be represented by a signed 64-bit integer (2^64-1). This is because the most significant bit of a signed integer is used to indicate the sign, leaving 63 bits for the actual value.

In cryptography, 2^63 is also the size of the key space for a symmetric encryption algorithm called DES (Data Encryption Standard). This means that there are 2^63 possible keys that can be used to encrypt and decrypt data, making it very difficult to crack.