205387544309 has 2 divisors, whose sum is σ = 205387544310. Its totient is φ = 205387544308.

The previous prime is 205387544261. The next prime is 205387544311. The reversal of 205387544309 is 903445783502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 189505243684 + 15882300625 = 435322^2 + 126025^2 .

It is a cyclic number.

It is not a de Polignac number, because 205387544309 - 2²⁸ = 205119108853 is a prime.

Together with 205387544311, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205387544339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102693772154 + 102693772155.

It is an arithmetic number, because the mean of its divisors is an integer number (102693772155).

Almost surely, 2^205387544309 is an apocalyptic number.

It is an amenable number.

205387544309 is a deficient number, since it is larger than the sum of its proper divisors (1).

205387544309 is an equidigital number, since it uses as much as digits as its factorization.

205387544309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3628800, while the sum is 50.

The spelling of 205387544309 in words is "two hundred five billion, three hundred eighty-seven million, five hundred forty-four thousand, three hundred nine".