204386821 has 2 divisors, whose sum is σ = 204386822. Its totient is φ = 204386820.

The previous prime is 204386789. The next prime is 204386827. The reversal of 204386821 is 128683402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 204089796 + 297025 = 14286^2 + 545^2 .

It is a cyclic number.

It is not a de Polignac number, because 204386821 - 2⁵ = 204386789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (204386827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102193410 + 102193411.

It is an arithmetic number, because the mean of its divisors is an integer number (102193411).

Almost surely, 2^204386821 is an apocalyptic number.

It is an amenable number.

204386821 is a deficient number, since it is larger than the sum of its proper divisors (1).

204386821 is an equidigital number, since it uses as much as digits as its factorization.

204386821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18432, while the sum is 34.

The square root of 204386821 is about 14296.3918874659. The cubic root of 204386821 is about 589.0483759172.

The spelling of 204386821 in words is "two hundred four million, three hundred eighty-six thousand, eight hundred twenty-one".