204391921 has 2 divisors, whose sum is σ = 204391922. Its totient is φ = 204391920.

The previous prime is 204391909. The next prime is 204391927. The reversal of 204391921 is 129193402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 141348321 + 63043600 = 11889^2 + 7940^2 .

It is a cyclic number.

It is not a de Polignac number, because 204391921 - 2¹¹ = 204389873 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (204391927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102195960 + 102195961.

It is an arithmetic number, because the mean of its divisors is an integer number (102195961).

Almost surely, 2^204391921 is an apocalyptic number.

It is an amenable number.

204391921 is a deficient number, since it is larger than the sum of its proper divisors (1).

204391921 is an equidigital number, since it uses as much as digits as its factorization.

204391921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 204391921 is about 14296.5702530362. The cubic root of 204391921 is about 589.0532753227.

The spelling of 204391921 in words is "two hundred four million, three hundred ninety-one thousand, nine hundred twenty-one".