205111310561 has 4 divisors (see below), whose sum is σ = 208473791124. Its totient is φ = 201748830000.

The previous prime is 205111310557. The next prime is 205111310611. The reversal of 205111310561 is 165013111502.

205111310561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 35247809536 + 169863501025 = 187744^2 + 412145^2 .

It is a cyclic number.

It is not a de Polignac number, because 205111310561 - 2² = 205111310557 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 205111310561.

It is not an unprimeable number, because it can be changed into a prime (205111310501) 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 3 ways as a sum of consecutive naturals, for example, 1681240190 + ... + 1681240311.

It is an arithmetic number, because the mean of its divisors is an integer number (52118447781).

Almost surely, 2^205111310561 is an apocalyptic number.

It is an amenable number.

205111310561 is a deficient number, since it is larger than the sum of its proper divisors (3362480563).

205111310561 is an equidigital number, since it uses as much as digits as its factorization.

205111310561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3362480562.

The product of its (nonzero) digits is 900, while the sum is 26.

The spelling of 205111310561 in words is "two hundred five billion, one hundred eleven million, three hundred ten thousand, five hundred sixty-one".