205985 has 8 divisors (see below), whose sum is σ = 266280. Its totient is φ = 152064.

The previous prime is 205981. The next prime is 205991. The reversal of 205985 is 589502.

It can be written as a sum of positive squares in 4 ways, for example, as 18496 + 187489 = 136^2 + 433^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 205985 - 2² = 205981 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 205985.

It is not an unprimeable number, because it can be changed into a prime (205981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1520 + ... + 1649.

It is an arithmetic number, because the mean of its divisors is an integer number (33285).

2²⁰⁵⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

205985 is a deficient number, since it is larger than the sum of its proper divisors (60295).

205985 is a wasteful number, since it uses less digits than its factorization.

205985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3187.

The product of its (nonzero) digits is 3600, while the sum is 29.

The square root of 205985 is about 453.8557039412. The cubic root of 205985 is about 59.0579723207.

The spelling of 205985 in words is "two hundred five thousand, nine hundred eighty-five".