205999866 has 12 divisors (see below), whose sum is σ = 446333082. Its totient is φ = 68666616.

The previous prime is 205999841. The next prime is 205999877. The reversal of 205999866 is 668999502.

205999866 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 175430025 + 30569841 = 13245^2 + 5529^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5722201 + ... + 5722236.

Almost surely, 2^205999866 is an apocalyptic number.

205999866 is an abundant number, since it is smaller than the sum of its proper divisors (240333216).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

205999866 is a wasteful number, since it uses less digits than its factorization.

205999866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11444445 (or 11444442 counting only the distinct ones).

The product of its (nonzero) digits is 2099520, while the sum is 54.

The square root of 205999866 is about 14352.6954262954. The cubic root of 205999866 is about 590.5939303048.

The spelling of 205999866 in words is "two hundred five million, nine hundred ninety-nine thousand, eight hundred sixty-six".