205817189 has 2 divisors, whose sum is σ = 205817190. Its totient is φ = 205817188.

The previous prime is 205817173. The next prime is 205817191. The reversal of 205817189 is 981718502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 128640964 + 77176225 = 11342^2 + 8785^2 .

It is a cyclic number.

It is not a de Polignac number, because 205817189 - 2⁴ = 205817173 is a prime.

Together with 205817191, 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 (205817119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102908594 + 102908595.

It is an arithmetic number, because the mean of its divisors is an integer number (102908595).

Almost surely, 2^205817189 is an apocalyptic number.

It is an amenable number.

205817189 is a deficient number, since it is larger than the sum of its proper divisors (1).

205817189 is an equidigital number, since it uses as much as digits as its factorization.

205817189 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40320, while the sum is 41.

The square root of 205817189 is about 14346.3301579184. The cubic root of 205817189 is about 590.4193026279.

The spelling of 205817189 in words is "two hundred five million, eight hundred seventeen thousand, one hundred eighty-nine".