665511556120 has 16 divisors (see below), whose sum is σ = 1497401001360. Its totient is φ = 266204622432.

The previous prime is 665511556079. The next prime is 665511556123. The reversal of 665511556120 is 21655115566.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665511556123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8318894412 + ... + 8318894491.

It is an arithmetic number, because the mean of its divisors is an integer number (93587562585).

Almost surely, 2^665511556120 is an apocalyptic number.

It is an amenable number.

665511556120 is an abundant number, since it is smaller than the sum of its proper divisors (831889445240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665511556120 is a wasteful number, since it uses less digits than its factorization.

665511556120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16637788914 (or 16637788910 counting only the distinct ones).

The product of its (nonzero) digits is 270000, while the sum is 43.

The spelling of 665511556120 in words is "six hundred sixty-five billion, five hundred eleven million, five hundred fifty-six thousand, one hundred twenty".