665168261585 has 32 divisors (see below), whose sum is σ = 804448139040. Its totient is φ = 527992363008.

The previous prime is 665168261581. The next prime is 665168261683. The reversal of 665168261585 is 585162861566.

It can be written as a sum of positive squares in 16 ways, for example, as 286944491584 + 378223770001 = 535672^2 + 614999^2 .

It is a cyclic number.

It is not a de Polignac number, because 665168261585 - 2² = 665168261581 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (665168261581) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 589165301 + ... + 589166429.

It is an arithmetic number, because the mean of its divisors is an integer number (25139004345).

Almost surely, 2^665168261585 is an apocalyptic number.

It is an amenable number.

665168261585 is a deficient number, since it is larger than the sum of its proper divisors (139279877455).

665168261585 is a wasteful number, since it uses less digits than its factorization.

665168261585 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2837.

The product of its digits is 20736000, while the sum is 59.

The spelling of 665168261585 in words is "six hundred sixty-five billion, one hundred sixty-eight million, two hundred sixty-one thousand, five hundred eighty-five".