19 (number)

19

← 10 11 12 13 14 15 16 17 18 19 →

List of numbers — Integers

← 0 10 20 30 40 50 60 70 80 90 →

nineteen

19th
(nineteenth)

1, 19

XIX

10011₂

201₃

103₄

34₅

31₆

23₈

17₁₂

13₁₆

J₂₀

J₃₆

19 (nineteen) is the natural number following 18 and preceding 20. It is a prime number.

In a 24-hour clock, the nineteenth hour is in conventional language called seven or seven o'clock.

19 is the 8th prime number. The sequence continues 23, 29, 31, 37, ... .

19 is the seventh Mersenne prime exponent.

19 is the fifth happy number and the third happy prime.

19 is the aliquot sum of two odd discrete semiprimes, 65 and 77 and is the base of the 19-aliquot tree.

19 is the maximum number of fourth powers needed to sum up to any natural number. It is the fourth value of g(k).

19 is the lowest prime centered triangular number, a centered hexagonal number and a Heegner number.

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.

19 is The TCP/IP port used for chargen.

In the Bábí and Bahá'í faiths, a group of 19 is called a Váhid, a Unity (Arabic: واحد wāhid, "one"). The numerical value of this word in the Abjad numeral system is 19.

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