204731561 has 16 divisors (see below), whose sum is σ = 225244800. Its totient is φ = 185219328.

The previous prime is 204731543. The next prime is 204731587. The reversal of 204731561 is 165137402.

It is a de Polignac number, because none of the positive numbers 2^k-204731561 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (204731521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 128870 + ... + 130448.

It is an arithmetic number, because the mean of its divisors is an integer number (14077800).

Almost surely, 2^204731561 is an apocalyptic number.

It is an amenable number.

204731561 is a deficient number, since it is larger than the sum of its proper divisors (20513239).

204731561 is a wasteful number, since it uses less digits than its factorization.

204731561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1888.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 204731561 is about 14308.4436959440. The cubic root of 204731561 is about 589.3793732402.

Adding to 204731561 its reverse (165137402), we get a palindrome (369868963).

The spelling of 204731561 in words is "two hundred four million, seven hundred thirty-one thousand, five hundred sixty-one".