83 (number)
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83 is a natural number that follows 82 and precedes 84. It is written in Arabic-Hindu numerals as "83", and in Roman numerals as LXXXIII. In binary notation it is 1010011.
The most notable property of 83 is that it is a prime number, meaning it cannot be divided by any number other than 1 and itself. It is the 23rd prime number starting from 2. The prime numbers adjacent to it are 79 before and 89 after.
Mathematical properties
83 is a safe prime, because when 1 is subtracted and the result divided by 2, the quotient is 41—which is also prime. It is likewise a Sophie Germain prime, since 2 × 83 + 1 = 167, which is prime. The sum of its digits (8 + 3) is 11, which is also prime.
83 can be expressed as the sum of three perfect squares, for example 9 + 25 + 49 = 83. Like all primes except 2 and 3, it takes the form 6n ± 1—in this case 6 × 14 − 1.
Other uses
In the periodic table, 83 is the atomic number of bismuth (Bi), a heavy metallic element. The number is also used to refer to years in historical contexts, such as 83 AD and 83 BC.