204031661 has 4 divisors (see below), whose sum is σ = 204675612. Its totient is φ = 203387712.

The previous prime is 204031657. The next prime is 204031669. The reversal of 204031661 is 166130402.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166130402 = 2 ⋅83065201.

It can be written as a sum of positive squares in 2 ways, for example, as 14969161 + 189062500 = 3869^2 + 13750^2 .

It is a cyclic number.

It is not a de Polignac number, because 204031661 - 2² = 204031657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204031669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 321500 + ... + 322133.

It is an arithmetic number, because the mean of its divisors is an integer number (51168903).

Almost surely, 2^204031661 is an apocalyptic number.

It is an amenable number.

204031661 is a deficient number, since it is larger than the sum of its proper divisors (643951).

204031661 is an equidigital number, since it uses as much as digits as its factorization.

204031661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 643950.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 204031661 is about 14283.9651707780. The cubic root of 204031661 is about 588.7069845046.

The spelling of 204031661 in words is "two hundred four million, thirty-one thousand, six hundred sixty-one".