206431135209 has 12 divisors (see below), whose sum is σ = 321115099396. Its totient is φ = 127034544672.

The previous prime is 206431135199. The next prime is 206431135223. The reversal of 206431135209 is 902531134602.

206431135209 is a `hidden beast` number, since 2 + 0 + 6 + 431 + 13 + 5 + 209 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 28958509584 + 177472625625 = 170172^2 + 421275^2 .

It is not a de Polignac number, because 206431135209 - 2⁸ = 206431134953 is a prime.

It is a super-2 number, since 2×206431135209² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (206431135409) 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, 882184222 + ... + 882184455.

Almost surely, 2^206431135209 is an apocalyptic number.

It is an amenable number.

206431135209 is a deficient number, since it is larger than the sum of its proper divisors (114683964187).

206431135209 is a wasteful number, since it uses less digits than its factorization.

206431135209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1764368696 (or 1764368693 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 36.

The spelling of 206431135209 in words is "two hundred six billion, four hundred thirty-one million, one hundred thirty-five thousand, two hundred nine".