205054021 has 2 divisors, whose sum is σ = 205054022. Its totient is φ = 205054020.

The previous prime is 205054013. The next prime is 205054043. The reversal of 205054021 is 120450502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 103245921 + 101808100 = 10161^2 + 10090^2 .

It is a cyclic number.

It is not a de Polignac number, because 205054021 - 2³ = 205054013 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 205054021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205054081) 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, 102527010 + 102527011.

It is an arithmetic number, because the mean of its divisors is an integer number (102527011).

Almost surely, 2^205054021 is an apocalyptic number.

It is an amenable number.

205054021 is a deficient number, since it is larger than the sum of its proper divisors (1).

205054021 is an equidigital number, since it uses as much as digits as its factorization.

205054021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 205054021 is about 14319.7074341622. The cubic root of 205054021 is about 589.6886425742.

The spelling of 205054021 in words is "two hundred five million, fifty-four thousand, twenty-one".