383
This number is a prime.
 
The only known multidigit palindromic Woodall prime. 
 
Sexy primes are such that n and n + 6 are both prime. The pair (383, 389) for example. 
 
The first multidigit palindromic prime to appear in the decimal expansion of π.  [Wu]
 
The sum of the first three 3-digit palindromic primes.  [Vouzaxakis]
 
383 is the smallest p(n) such that the continued fraction expansion of [p(n)+sqrt(p(n+1))]/p(n+2) has a prime number of coefficients in its periodic portion.  [Rupinski]
 
The smallest prime which can be represented as sum of a prime and its reversal (241 + 142 = 383).  [Gupta]
 
383 = 6*2^6 - 1.  [Noll]
 
The smallest palindromic Pillai prime. 
 
Together with 191, this prime forms a palindromic Sophie Germain pair: i.e., 2(191)+1 = 383. Less known is the fact that 383 divides the Mersenne number 2^191-1.  [De Geest]
 
383 = prime(3*8*3) + sigma(3+8+3). Note that 383 is the earliest number (coincidentally prime) with this property.  [Firoozbakht]
 
The smallest prime of the form 383*2^n+1 is titanic. 
 
The product of the nonzero even digits minus 1.  [Silva]
 
An aqueous solution of hydrochloric acid boils at a higher
temperature than pure water and reaches a maximum boiling
(or azeotropic) point of 383 K.  [Beedassy]
 
The sum of three consecutive balanced primes (53 + 157 + 173).  [Silva]
 
383 = 3^5 + 1^4 + 4^1 + 1^9 + 5^3 + 9^1. Note the first six digits of
the decimal expansion of π as bases and exponents.  [Silva]
 
The ordered concatenation of all reflectable primes up to
383 is a reflectable prime. Can you find a larger example? 
 
In the movie "Superman II," 383 is Otis' and Lex Luthor's prison cell number. 
 
The smallest palindromic curved-digit-prime.  [Bajpai]
 
The largest prime in the binary sequence 101, 1011, 10111..., 101111111. The only one which is not prime is,
ironically, the 7 digit 1011111 with 5 consecutive ones.  [Homewood]
 
383 is the only palindromic “almost evenian prime” less than a googol, i.e., a prime that can be represented as the product of first n positive even numbers minus 1, (case n=4), i.e., 2*4*6*8-1 = 383.  [Loungrides]
 
1966322 has a Collatz trajectory length of 383 and its
largest prime factor is 383. Are there any larger examples
of this property?  [Gaydos]
 
Difference in the number of digits of Mersenne prime M22 (i.e., 2993) and the number of digits of its immediate successor M23 (i.e., 3376).  [Harrison]
 
David Darling's The Universal Book of Mathematics is a 383-page book.  [Olry]
 
Nolan Ryan holds the Major League Baseball single-season
strikeout record at 383.  [Enberg]
 
The smallest n-digit palindromic prime that is the sum of n
consecutive n-digit palindromic primes, i.e., (101 + 131 +
151), (case n=3).  [Bajpai]
 
The first three consecutive nonpalindromic balanced primes sum to give the (3+8+3)th palindromic prime 383. Note that
these three primes form a prime palindromic set {3, 5, 17, 71, 5, 3}.  [Worrom]