205634861 has 2 divisors, whose sum is σ = 205634862. Its totient is φ = 205634860.

The previous prime is 205634831. The next prime is 205634959. The reversal of 205634861 is 168436502.

205634861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 118679236 + 86955625 = 10894^2 + 9325^2 .

It is a cyclic number.

It is not a de Polignac number, because 205634861 - 2¹⁰ = 205633837 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205634831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102817430 + 102817431.

It is an arithmetic number, because the mean of its divisors is an integer number (102817431).

Almost surely, 2^205634861 is an apocalyptic number.

It is an amenable number.

205634861 is a deficient number, since it is larger than the sum of its proper divisors (1).

205634861 is an equidigital number, since it uses as much as digits as its factorization.

205634861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 35.

The square root of 205634861 is about 14339.9742328918. The cubic root of 205634861 is about 590.2449055090.

The spelling of 205634861 in words is "two hundred five million, six hundred thirty-four thousand, eight hundred sixty-one".