206681409 has 32 divisors (see below), whose sum is σ = 335347200. Its totient is φ = 124768080.

The previous prime is 206681389. The next prime is 206681417. The reversal of 206681409 is 904186602.

It is not a de Polignac number, because 206681409 - 2⁹ = 206680897 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (206681429) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 82822 + ... + 85280.

It is an arithmetic number, because the mean of its divisors is an integer number (10479600).

Almost surely, 2^206681409 is an apocalyptic number.

It is an amenable number.

206681409 is a deficient number, since it is larger than the sum of its proper divisors (128665791).

206681409 is a wasteful number, since it uses less digits than its factorization.

206681409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2762 (or 2756 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 206681409 is about 14376.4185039251. The cubic root of 206681409 is about 591.2445327846.

The spelling of 206681409 in words is "two hundred six million, six hundred eighty-one thousand, four hundred nine".