83

83 is the natural number that comes after 82 and before 84. In mathematics, 83 is a prime number, the 23rd prime. It is also a safe prime, since (83−1)/2 = 41 is prime, and a Sophie Germain prime, since 2×83 + 1 = 167 is prime as well. The number is odd and congruent to 3 modulo 4.

In different numeral systems, 83 is represented as 1010011 in binary, 123 in octal, and 53 in hexadecimal. In Roman numerals it is written as LXXXIII. The decimal value 83 corresponds to the ASCII code for the uppercase letter S (Unicode code point U+0053).

In science, the atomic number 83 designates the element bismuth, symbol Bi. Bismuth is a heavy, brittle metal with a distinctive pinkish alloy surface. It is highly diamagnetic and has relatively low toxicity compared with many other heavy metals. Bismuth occurs naturally in minerals and sometimes as a native metal. It is used in a variety of applications, including cosmetics, pharmaceuticals (notably bismuth subsalicylate), and certain alloys and coatings.

Overall, 83 is notable primarily for its mathematical properties as a prime and for its identification with the element bismuth in the periodic table, where it carries both practical uses and historic significance.