205166507210221 has 4 divisors (see below), whose sum is σ = 205175315309212. Its totient is φ = 205157699111232.

The previous prime is 205166507210141. The next prime is 205166507210239. The reversal of 205166507210221 is 122012705661502.

It is a happy number.

205166507210221 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 119142922698121 + 86023584512100 = 10915261^2 + 9274890^2 .

It is a cyclic number.

It is not a de Polignac number, because 205166507210221 - 2¹⁵ = 205166507177453 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 (205166507210921) 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, 4404014556 + ... + 4404061141.

It is an arithmetic number, because the mean of its divisors is an integer number (51293828827303).

Almost surely, 2^{205166507210221} is an apocalyptic number.

It is an amenable number.

205166507210221 is a deficient number, since it is larger than the sum of its proper divisors (8808098991).

205166507210221 is an equidigital number, since it uses as much as digits as its factorization.

205166507210221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8808098990.

The product of its (nonzero) digits is 100800, while the sum is 40.

The spelling of 205166507210221 in words is "two hundred five trillion, one hundred sixty-six billion, five hundred seven million, two hundred ten thousand, two hundred twenty-one".