665636378873 has 4 divisors (see below), whose sum is σ = 665639079588. Its totient is φ = 665633678160.

The previous prime is 665636378863. The next prime is 665636378917. The reversal of 665636378873 is 378873636566.

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 317721614224 + 347914764649 = 563668^2 + 589843^2 .

It is a cyclic number.

It is not a de Polignac number, because 665636378873 - 2⁶ = 665636378809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665636378833) 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, 938858 + ... + 1487523.

It is an arithmetic number, because the mean of its divisors is an integer number (166409769897).

Almost surely, 2^665636378873 is an apocalyptic number.

It is an amenable number.

665636378873 is a deficient number, since it is larger than the sum of its proper divisors (2700715).

665636378873 is a wasteful number, since it uses less digits than its factorization.

665636378873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2700714.

The product of its digits is 548674560, while the sum is 68.

The spelling of 665636378873 in words is "six hundred sixty-five billion, six hundred thirty-six million, three hundred seventy-eight thousand, eight hundred seventy-three".