665209389 has 16 divisors (see below), whose sum is σ = 956430272. Its totient is φ = 408820608.

The previous prime is 665209387. The next prime is 665209423. The reversal of 665209389 is 983902566.

665209389 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 665209389 - 2¹ = 665209387 is a prime.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665209387) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19857 + ... + 41529.

It is an arithmetic number, because the mean of its divisors is an integer number (59776892).

Almost surely, 2^665209389 is an apocalyptic number.

It is an amenable number.

665209389 is a deficient number, since it is larger than the sum of its proper divisors (291220883).

665209389 is a wasteful number, since it uses less digits than its factorization.

665209389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22476.

The product of its (nonzero) digits is 699840, while the sum is 48.

The square root of 665209389 is about 25791.6534754947. The cubic root of 665209389 is about 872.9434757250.

The spelling of 665209389 in words is "six hundred sixty-five million, two hundred nine thousand, three hundred eighty-nine".