Mathematics
19 is the 8th smallest prime number. The sequence continues 23, 29, 31, 37...
19 is the seventh Mersenne prime exponent.
19 is the aliquot sum of two odd discrete semiprimes, 65 and 77 and is the base of the 19-aliquot tree.
19 is a centered triangular number, centered hexagonal number and a Heegner number.
You can make the number 19 by adding or subtracting but not multiplying (whole numbers), 19 can also be made by division.
The only non-trivial normal magic hexagon contains 19 hexagons (the other being 1).
19 is the first number with more than one digit that can be written from base 2 to base 19 using only the digits 0 to 9; the other number is 20.
Read more about this topic: 19 (number)
Famous quotes containing the word mathematics:
“... though mathematics may teach a man how to build a bridge, it is what the Scotch Universities call the humanities, that teach him to be civil and sweet-tempered.”
—Amelia E. Barr (1831–1919)
“In mathematics he was greater
Than Tycho Brahe, or Erra Pater:
For he, by geometric scale,
Could take the size of pots of ale;
Resolve, by sines and tangents straight,
If bread and butter wanted weight;
And wisely tell what hour o’ th’ day
The clock doth strike, by algebra.”
—Samuel Butler (1612–1680)
“The three main medieval points of view regarding universals are designated by historians as realism, conceptualism, and nominalism. Essentially these same three doctrines reappear in twentieth-century surveys of the philosophy of mathematics under the new names logicism, intuitionism, and formalism.”
—Willard Van Orman Quine (b. 1908)