224 (two hundred
ndtwenty-four) is the natural number following
223 and preceding
225.
In mathematics
224 is a
practical number,
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
In number theory, a branch of mathematics, the Carmichael function of a positive integer is the smallest positive integer such that
:a^m \equiv 1 \pmod
holds for every integer coprime to . In algebraic terms, is the exponent of a group, expone ...
.
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
he English-language version ofWikipedia
Wikipedia is a free content, free Online content, online encyclopedia that is written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the wiki software MediaWiki. Founded by Jimmy Wales and La ...
". That distinction now belongs to
315.
In other areas
In the
SHA-2
SHA-2 (Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression ...
family of six
cryptographic hash function
A cryptographic hash function (CHF) is a hash algorithm (a map (mathematics), map of an arbitrary binary string to a binary string with a fixed size of n bits) that has special properties desirable for a cryptography, cryptographic application: ...
s, the weakest is SHA-224, named because it produces 224-bit hash values. 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
In cryptography, Triple DES (3DES or TDES), officially the Triple Data Encryption Algorithm (TDEA or Triple DEA), is a symmetric-key block cipher, which applies the DES cipher algorithm three times to each data block. The 56-bit key of the Dat ...
.
The ancient Phoenician
shekel
A shekel or sheqel (; , , plural , ) is an ancient Mesopotamian coin, usually of silver. A shekel was first a unit of weight—very roughly 11 grams (0.35 ozt)—and became currency in ancient Tyre, Carthage and Hasmonean Judea.
Name
The wo ...
was a standardized measure of
silver
Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...
, equal to 224 grains, although other forms of the shekel employed in other ancient cultures (including the Babylonians and Hebrews) had different measures. Likely not coincidentally, as far as ancient
Burma
Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and ha ...
and
Thailand
Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
, silver was measured in a unit called a ''tikal'', equal to 224 grains.
See also
*
224 (disambiguation)
References
{{Integers, 2
Integers