206391866 has 16 divisors (see below), whose sum is σ = 329218344. Its totient is φ = 96705024.

The previous prime is 206391863. The next prime is 206391877. The reversal of 206391866 is 668193602.

It can be written as a sum of positive squares in 4 ways, for example, as 196812841 + 9579025 = 14029^2 + 3095^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (206391863) 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 7 ways as a sum of consecutive naturals, for example, 5105 + ... + 20948.

Almost surely, 2^206391866 is an apocalyptic number.

206391866 is a deficient number, since it is larger than the sum of its proper divisors (122826478).

206391866 is a wasteful number, since it uses less digits than its factorization.

206391866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26305.

The product of its (nonzero) digits is 93312, while the sum is 41.

The square root of 206391866 is about 14366.3449074565. The cubic root of 206391866 is about 590.9683093931.

The spelling of 206391866 in words is "two hundred six million, three hundred ninety-one thousand, eight hundred sixty-six".