205365566645 has 4 divisors (see below), whose sum is σ = 246438679980. Its totient is φ = 164292453312.

The previous prime is 205365566639. The next prime is 205365566647. The reversal of 205365566645 is 546665563502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 546665563502 = 2 ⋅273332781751.

It can be written as a sum of positive squares in 2 ways, for example, as 157468493329 + 47897073316 = 396823^2 + 218854^2 .

It is a cyclic number.

It is not a de Polignac number, because 205365566645 - 2⁴ = 205365566629 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205365566647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20536556660 + ... + 20536556669.

It is an arithmetic number, because the mean of its divisors is an integer number (61609669995).

Almost surely, 2^205365566645 is an apocalyptic number.

It is an amenable number.

205365566645 is a deficient number, since it is larger than the sum of its proper divisors (41073113335).

205365566645 is an equidigital number, since it uses as much as digits as its factorization.

205365566645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41073113334.

The product of its (nonzero) digits is 19440000, while the sum is 53.

The spelling of 205365566645 in words is "two hundred five billion, three hundred sixty-five million, five hundred sixty-six thousand, six hundred forty-five".