204430021 has 2 divisors, whose sum is σ = 204430022. Its totient is φ = 204430020.

The previous prime is 204430013. The next prime is 204430043. The reversal of 204430021 is 120034402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 135722500 + 68707521 = 11650^2 + 8289^2 .

It is a cyclic number.

It is not a de Polignac number, because 204430021 - 2³ = 204430013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 204429977 and 204430004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (204430001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102215010 + 102215011.

It is an arithmetic number, because the mean of its divisors is an integer number (102215011).

Almost surely, 2^204430021 is an apocalyptic number.

It is an amenable number.

204430021 is a deficient number, since it is larger than the sum of its proper divisors (1).

204430021 is an equidigital number, since it uses as much as digits as its factorization.

204430021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 204430021 is about 14297.9026783651. The cubic root of 204430021 is about 589.0898741852.

Adding to 204430021 its reverse (120034402), we get a palindrome (324464423).

The spelling of 204430021 in words is "two hundred four million, four hundred thirty thousand, twenty-one".