224 (two hundred [and] twenty-four) is the natural number following 223 and preceding 225.
| Number: | 224 |
| Prime: | No |
224 is a practical number,[1] and a sum of two positive cubes . It is also, making it one of the smallest numbers to be the sum of distinct positive cubes in more than one way.
224 is the smallest k with λ(k) = 24, where λ(k) is the Carmichael function.[2]
The mathematician and philosopher Alex Bellos suggested in 2014 that a candidate for the lowest uninteresting number would be 224 because it was, at the time, "the lowest number not to have its own page on [the English-language version of] Wikipedia".[3] That distinction now belongs to 315.
In the SHA-2 family of six cryptographic hash functions, the weakest is SHA-224, named because it produces 224-bit hash values.[4] It was defined in this way so that the number of bits of security it provides (half of its output length, 112 bits) would match the key length of two-key Triple DES.[5]
The ancient Phoenician shekel was a standardized measure of silver, equal to 224 grains, although other forms of the shekel employed in other ancient cultures (including the Babylonians and Hebrews) had different measures.[6] Likely not coincidentally, as far as ancient Burma and Thailand, silver was measured in a unit called a tikal, equal to 224 grains.[7]