206406509 has 4 divisors (see below), whose sum is σ = 206495580. Its totient is φ = 206317440.

The previous prime is 206406449. The next prime is 206406611. The reversal of 206406509 is 905604602.

206406509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4141225 + 202265284 = 2035^2 + 14222^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206406509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206706509) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40964 + ... + 45725.

It is an arithmetic number, because the mean of its divisors is an integer number (51623895).

Almost surely, 2^206406509 is an apocalyptic number.

It is an amenable number.

206406509 is a deficient number, since it is larger than the sum of its proper divisors (89071).

206406509 is an equidigital number, since it uses as much as digits as its factorization.

206406509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89070.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 206406509 is about 14366.8545270007. The cubic root of 206406509 is about 590.9822849832.

The spelling of 206406509 in words is "two hundred six million, four hundred six thousand, five hundred nine".