204242021 has 2 divisors, whose sum is σ = 204242022. Its totient is φ = 204242020.

The previous prime is 204242009. The next prime is 204242023. The reversal of 204242021 is 120242402.

It is a happy number.

204242021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 178089025 + 26152996 = 13345^2 + 5114^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-204242021 is a prime.

Together with 204242023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (204242023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102121010 + 102121011.

It is an arithmetic number, because the mean of its divisors is an integer number (102121011).

Almost surely, 2^204242021 is an apocalyptic number.

It is an amenable number.

204242021 is a deficient number, since it is larger than the sum of its proper divisors (1).

204242021 is an equidigital number, since it uses as much as digits as its factorization.

204242021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 204242021 is about 14291.3267753557. The cubic root of 204242021 is about 588.9092372081.

Adding to 204242021 its reverse (120242402), we get a palindrome (324484423).

The spelling of 204242021 in words is "two hundred four million, two hundred forty-two thousand, twenty-one".