205442309 has 2 divisors, whose sum is σ = 205442310. Its totient is φ = 205442308.

The previous prime is 205442299. The next prime is 205442357. The reversal of 205442309 is 903244502.

205442309 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., 142874209 + 62568100 = 11953^2 + 7910^2 .

It is a cyclic number.

It is not a de Polignac number, because 205442309 - 2²⁴ = 188665093 is a prime.

It is a super-3 number, since 3×205442309³ (a number of 26 digits) contains 333 as substring.

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 (205442009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102721154 + 102721155.

It is an arithmetic number, because the mean of its divisors is an integer number (102721155).

Almost surely, 2^205442309 is an apocalyptic number.

It is an amenable number.

205442309 is a deficient number, since it is larger than the sum of its proper divisors (1).

205442309 is an equidigital number, since it uses as much as digits as its factorization.

205442309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 205442309 is about 14333.2588408917. The cubic root of 205442309 is about 590.0606171560.

The spelling of 205442309 in words is "two hundred five million, four hundred forty-two thousand, three hundred nine".