# 19

This number is a prime.

Just showing those entries submitted by 'Das': (Click here to show all)

19 is the smallest prime p such that 10*p {+ 1, 3, 7, and 9} are all primes. [Das]

The first prime repfigit number. A repfigit (*rep*etitive *fi*bonacci-like di*git*) number is an *n*-digit integer *N* with the following property: if a Fibonacci-like sequence (in which each term in the sequence is the sum of the *n* previous terms) is formed, with the first *n* terms being the decimal digits of the number *N*, then *N* itself occurs as a term in the sequence. For example, if the digits of 19 start a Fibonacci-like sequence, then 19 appears as a term: 1, 9, 10, 19. These are also known as Keith numbers. [Beedassy]

The largest prime that is palindromic in Roman numerals alphabetically is XIX (19). [Beedassy]

19 is the "age of
majority" adopted under federal jurisdiction in two US
states, *viz*., Nebraska, Alabama. [Beedassy]

The index *p* of the largest known Mersenne prime
*M*_{p} = 2^{p} - 1
having an associated perfect number
*M*_{p}*2^{p - 1} that
is short of a prime by 1. [Beedassy]

The number of topologically distinct planar configurations without discontinuities that are possible using six matches. [Beedassy]

The number of letters in the anagrammatic title "A Superb Mosaic - Dare it !" that fittingly qualifies the "PRIME CURIOS DATABASE" with a poetic touch. [Beedassy]

Pandigital palindromic primes start as 19-digit numbers. [Beedassy]