205663985 has 4 divisors (see below), whose sum is σ = 246796788. Its totient is φ = 164531184.

The previous prime is 205663981. The next prime is 205663987. The reversal of 205663985 is 589366502.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 142874209 + 62789776 = 11953^2 + 7924^2 .

It is a cyclic number.

It is not a de Polignac number, because 205663985 - 2² = 205663981 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205663981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20566394 + ... + 20566403.

It is an arithmetic number, because the mean of its divisors is an integer number (61699197).

Almost surely, 2^205663985 is an apocalyptic number.

It is an amenable number.

205663985 is a deficient number, since it is larger than the sum of its proper divisors (41132803).

205663985 is an equidigital number, since it uses as much as digits as its factorization.

205663985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41132802.

The product of its (nonzero) digits is 388800, while the sum is 44.

The square root of 205663985 is about 14340.9896799349. The cubic root of 205663985 is about 590.2727695930.

The spelling of 205663985 in words is "two hundred five million, six hundred sixty-three thousand, nine hundred eighty-five".