665647385 has 16 divisors (see below), whose sum is σ = 861275856. Its totient is φ = 490952448.

The previous prime is 665647379. The next prime is 665647399. The reversal of 665647385 is 583746566.

It can be written as a sum of positive squares in 8 ways, for example, as 9467929 + 656179456 = 3077^2 + 25616^2 .

It is a cyclic number.

It is not a de Polignac number, because 665647385 - 2⁴ = 665647369 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51167 + ... + 62843.

It is an arithmetic number, because the mean of its divisors is an integer number (53829741).

Almost surely, 2^665647385 is an apocalyptic number.

665647385 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

665647385 is a deficient number, since it is larger than the sum of its proper divisors (195628471).

665647385 is a wasteful number, since it uses less digits than its factorization.

665647385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12572.

The product of its digits is 3628800, while the sum is 50.

The square root of 665647385 is about 25800.1431197581. The cubic root of 665647385 is about 873.1350253690.

The spelling of 665647385 in words is "six hundred sixty-five million, six hundred forty-seven thousand, three hundred eighty-five".