83821 has 4 divisors (see below), whose sum is σ = 84700. Its totient is φ = 82944.
The previous prime is 83813. The next prime is 83833. The reversal of 83821 is 12838.
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.
It can be written as a sum of positive squares in 2 ways, for example, as 45796 + 38025 = 214^2 + 195^2 .
It is a 5-Lehmer number, since φ(83821) divides (83821-1)5.
It is a cyclic number.
It is not a de Polignac number, because 83821 - 23 = 83813 is a prime.
It is a Duffinian number.
It is a junction number, because it is equal to n+sod(n) for n = 83792 and 83801.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (83891) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 276 + ... + 493.
It is an arithmetic number, because the mean of its divisors is an integer number (21175).
283821 is an apocalyptic number.
It is an amenable number.
83821 is a deficient number, since it is larger than the sum of its proper divisors (879).
83821 is a wasteful number, since it uses less digits than its factorization.
83821 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 878.
The product of its digits is 384, while the sum is 22.
The square root of 83821 is about 289.5185658986. The cubic root of 83821 is about 43.7640607867.
The spelling of 83821 in words is "eighty-three thousand, eight hundred twenty-one".
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