205680987 has 12 divisors (see below), whose sum is σ = 297533704. Its totient is φ = 136918080.

The previous prime is 205680967. The next prime is 205680989. The reversal of 205680987 is 789086502.

205680987 is a `hidden beast` number, since 2 + 0 + 568 + 0 + 9 + 87 = 666.

It is not a de Polignac number, because 205680987 - 2¹⁰ = 205679963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205680989) 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 11 ways as a sum of consecutive naturals, for example, 10318 + ... + 22755.

Almost surely, 2^205680987 is an apocalyptic number.

205680987 is a deficient number, since it is larger than the sum of its proper divisors (91852717).

205680987 is a wasteful number, since it uses less digits than its factorization.

205680987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33770 (or 33767 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The square root of 205680987 is about 14341.5824440680. The cubic root of 205680987 is about 590.2890348636.

The spelling of 205680987 in words is "two hundred five million, six hundred eighty thousand, nine hundred eighty-seven".