53821 has 4 divisors (see below), whose sum is σ = 54432. Its totient is φ = 53212.

The previous prime is 53819. The next prime is 53831. The reversal of 53821 is 12835.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 53821 - 2¹ = 53819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (53831) 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, 145 + ... + 358.

It is an arithmetic number, because the mean of its divisors is an integer number (13608).

2⁵³⁸²¹ is an apocalyptic number.

It is an amenable number.

53821 is a deficient number, since it is larger than the sum of its proper divisors (611).

53821 is a wasteful number, since it uses less digits than its factorization.

53821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610.

The product of its digits is 240, while the sum is 19.

The square root of 53821 is about 231.9935343927. The cubic root of 53821 is about 37.7558212154.

The spelling of 53821 in words is "fifty-three thousand, eight hundred twenty-one".