204435251561 has 32 divisors (see below), whose sum is σ = 221054883840. Its totient is φ = 188380348416.

The previous prime is 204435251549. The next prime is 204435251567. The reversal of 204435251561 is 165152534402.

204435251561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 204435251561 - 2⁶ = 204435251497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (204435251567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 61408745 + ... + 61412073.

It is an arithmetic number, because the mean of its divisors is an integer number (6907965120).

Almost surely, 2^204435251561 is an apocalyptic number.

It is an amenable number.

204435251561 is a deficient number, since it is larger than the sum of its proper divisors (16619632279).

204435251561 is a wasteful number, since it uses less digits than its factorization.

204435251561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3833.

The product of its (nonzero) digits is 144000, while the sum is 38.

Adding to 204435251561 its reverse (165152534402), we get a palindrome (369587785963).

The spelling of 204435251561 in words is "two hundred four billion, four hundred thirty-five million, two hundred fifty-one thousand, five hundred sixty-one".