205909381 has 2 divisors, whose sum is σ = 205909382. Its totient is φ = 205909380.

The previous prime is 205909373. The next prime is 205909411. The reversal of 205909381 is 183909502.

205909381 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., 158986881 + 46922500 = 12609^2 + 6850^2 .

It is a cyclic number.

It is not a de Polignac number, because 205909381 - 2³ = 205909373 is a prime.

It is a super-2 number, since 2×205909381² = 84797346367606322, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 205909381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205909981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102954690 + 102954691.

It is an arithmetic number, because the mean of its divisors is an integer number (102954691).

Almost surely, 2^205909381 is an apocalyptic number.

It is an amenable number.

205909381 is a deficient number, since it is larger than the sum of its proper divisors (1).

205909381 is an equidigital number, since it uses as much as digits as its factorization.

205909381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 205909381 is about 14349.5428847054. The cubic root of 205909381 is about 590.5074452677.

The spelling of 205909381 in words is "two hundred five million, nine hundred nine thousand, three hundred eighty-one".