205039981 has 2 divisors, whose sum is σ = 205039982. Its totient is φ = 205039980.

The previous prime is 205039957. The next prime is 205040027. The reversal of 205039981 is 189930502.

205039981 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., 137241225 + 67798756 = 11715^2 + 8234^2 .

It is a cyclic number.

It is not a de Polignac number, because 205039981 - 2⁷ = 205039853 is a prime.

It is a super-2 number, since 2×205039981² = 84082787616960722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 205039981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205039931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102519990 + 102519991.

It is an arithmetic number, because the mean of its divisors is an integer number (102519991).

Almost surely, 2^205039981 is an apocalyptic number.

It is an amenable number.

205039981 is a deficient number, since it is larger than the sum of its proper divisors (1).

205039981 is an equidigital number, since it uses as much as digits as its factorization.

205039981 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 205039981 is about 14319.2171922909. The cubic root of 205039981 is about 589.6751836534.

The spelling of 205039981 in words is "two hundred five million, thirty-nine thousand, nine hundred eighty-one".