205689009 has 4 divisors (see below), whose sum is σ = 274252016. Its totient is φ = 137126004.

The previous prime is 205689007. The next prime is 205689017. The reversal of 205689009 is 900986502.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 205689009 - 2¹ = 205689007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205689007) 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, 34281499 + ... + 34281504.

It is an arithmetic number, because the mean of its divisors is an integer number (68563004).

Almost surely, 2^205689009 is an apocalyptic number.

It is an amenable number.

205689009 is a deficient number, since it is larger than the sum of its proper divisors (68563007).

205689009 is an equidigital number, since it uses as much as digits as its factorization.

205689009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68563006.

The product of its (nonzero) digits is 38880, while the sum is 39.

The square root of 205689009 is about 14341.8621175913. The cubic root of 205689009 is about 590.2967089436.

The spelling of 205689009 in words is "two hundred five million, six hundred eighty-nine thousand, nine".