206398609 has 2 divisors, whose sum is σ = 206398610. Its totient is φ = 206398608.

The previous prime is 206398607. The next prime is 206398631. The reversal of 206398609 is 906893602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 202208400 + 4190209 = 14220^2 + 2047^2 .

It is a cyclic number.

It is not a de Polignac number, because 206398609 - 2¹ = 206398607 is a prime.

Together with 206398607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (206398603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103199304 + 103199305.

It is an arithmetic number, because the mean of its divisors is an integer number (103199305).

Almost surely, 2^206398609 is an apocalyptic number.

It is an amenable number.

206398609 is a deficient number, since it is larger than the sum of its proper divisors (1).

206398609 is an equidigital number, since it uses as much as digits as its factorization.

206398609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 139968, while the sum is 43.

The square root of 206398609 is about 14366.5795859697. The cubic root of 206398609 is about 590.9747451376.

The spelling of 206398609 in words is "two hundred six million, three hundred ninety-eight thousand, six hundred nine".