Concept
16 (sixteen) is the natural number following 15 and preceding 17. 16 is a composite number, and a square number, being 42 = 4 × 4. It is the smallest number with exactly five divisors, its proper divisors being , , and . 16 is the first non-unitary fourth-power prime of the form p4 The aliquot sum of a 2-power (2n) is always one less than the 2-power itself therefore the aliquot sum of 16 is 15, within an aliquot sequence of four composite members (16,15,9,4,3,1,0) to the Prime in the 3-aliquot tree. In English speech, the numbers 16 and 60 are sometimes confused, as they sound very similar. Sixteen is the fourth power of two. For this reason, 16 was used in weighing light objects in several cultures. The British have 16 ounces in one pound; the Chinese used to have 16 liangs in one jin. In old days, weighing was done with a beam balance to make equal splits. It would be easier to split a heap of grains into sixteen equal parts through successive divisions than to split into ten parts. Chinese Taoists did finger computation on the trigrams and hexagrams by counting the finger tips and joints of the fingers with the tip of the thumb. Each hand can count up to 16 in such manner. The Chinese abacus uses two upper beads to represent the 5s and 5 lower beads to represent the 1s, the 7 beads can represent a hexadecimal digit from 0 to 15 in each column. Sixteen is an even number and the square of four. Sixteen is the fourth power of two. Sixteen is the only integer that equals mn and nm, for some unequal integers m and n (, , or vice versa). It has this property because . It is also equal to 32 (see tetration). Sixteen is the base of the hexadecimal number system, which is used extensively in computer science. Sixteen is the largest known integer n, for which is prime. It is the first Erdős–Woods number. There are 16 partially ordered sets with four unlabeled elements. The atomic number of sulfur Group 16 of the periodic table are the chalcogens In some computer programming languages, the size in bits of certain data types 16-bit computing A 16-bit integer can represent up to 65,536 values.