206505009 has 24 divisors (see below), whose sum is σ = 304686720. Its totient is φ = 134747712.

The previous prime is 206505007. The next prime is 206505023. The reversal of 206505009 is 900505602.

206505009 is a `hidden beast` number, since 2 + 0 + 650 + 5 + 0 + 0 + 9 = 666.

It is not a de Polignac number, because 206505009 - 2¹ = 206505007 is a prime.

It is not an unprimeable number, because it can be changed into a prime (206505007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 81252 + ... + 83754.

It is an arithmetic number, because the mean of its divisors is an integer number (12695280).

Almost surely, 2^206505009 is an apocalyptic number.

It is an amenable number.

206505009 is a deficient number, since it is larger than the sum of its proper divisors (98181711).

206505009 is a wasteful number, since it uses less digits than its factorization.

206505009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2701 (or 2698 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 27.

The square root of 206505009 is about 14370.2821475432. The cubic root of 206505009 is about 591.0762783008.

The spelling of 206505009 in words is "two hundred six million, five hundred five thousand, nine".