55021 has 2 divisors, whose sum is σ = 55022. Its totient is φ = 55020.

The previous prime is 55009. The next prime is 55049. The reversal of 55021 is 12055.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42025 + 12996 = 205^2 + 114^2 .

It is a cyclic number.

It is not a de Polignac number, because 55021 - 2¹¹ = 52973 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 54992 and 55010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27510 + 27511.

It is an arithmetic number, because the mean of its divisors is an integer number (27511).

2⁵⁵⁰²¹ is an apocalyptic number.

It is an amenable number.

55021 is a deficient number, since it is larger than the sum of its proper divisors (1).

55021 is an equidigital number, since it uses as much as digits as its factorization.

55021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 50, while the sum is 13.

The square root of 55021 is about 234.5655558687. The cubic root of 55021 is about 38.0343641130.

Adding to 55021 its reverse (12055), we get a palindrome (67076).

The spelling of 55021 in words is "fifty-five thousand, twenty-one".