19 (number)

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

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Nineteen is the 8th smallest prime number. The sequence continues 23, 29, 31, 37... 19 is the seventh Mersenne prime exponent.

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It is also a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 1, 9, 10, 19...

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With respect to divisibility, nineteen has a very simple test: 19 divides 100a + b if and only if it divides a + 4b.

Natural number: Natural number can mean either a positive integer (, , , , ...) or a non-negative integer (, , , , , ...)....

Prime number: In mathematics, a prime number (or prime) is a natural number greater than one whose only positive divisors are one and itself. Or for short: A prime number is a natural number with exactly two natural divisors. A natural number that is greater than one and is not a prime is called a composite numbe...

Mersenne prime: In mathematics, a Mersenne prime is a prime number that is one less than a power of two. For example, 3 = 4 − 1 = 22 − 1 is a Mersenne prime; so is 7 = 8 − 1 = 23 − 1. On the other hand, 15 = 16 − 1 = 24 − 1, for example, is not a prime, because 15 is divisible by...

19 (number) related Images and Photos (experimental)

Number 8 1949	Number 36	Number 23	Number 25
Number 23 (BD)	Number 18 1950	ABBA: Number Ones CD	ABBA: Number Ones CD
Number 23, The (DVD) (WS) (Rated/Unrated)	Summertime: Number 9A 1948	Tree Number Two	Gangster Number 1