665171173845 has 48 divisors (see below), whose sum is σ = 1163669328432. Its totient is φ = 351466536960.

The previous prime is 665171173763. The next prime is 665171173867. The reversal of 665171173845 is 548371171566.

665171173845 is a `hidden beast` number, since 6 + 6 + 517 + 11 + 73 + 8 + 45 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 139392462609 + 525778711236 = 373353^2 + 725106^2 .

It is not a de Polignac number, because 665171173845 - 2¹⁷ = 665171042773 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 665171173791 and 665171173800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12263385 + ... + 12317505.

It is an arithmetic number, because the mean of its divisors is an integer number (24243111009).

Almost surely, 2^665171173845 is an apocalyptic number.

It is an amenable number.

665171173845 is a deficient number, since it is larger than the sum of its proper divisors (498498154587).

665171173845 is a wasteful number, since it uses less digits than its factorization.

665171173845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56662 (or 56659 counting only the distinct ones).

The product of its digits is 4233600, while the sum is 54.

The spelling of 665171173845 in words is "six hundred sixty-five billion, one hundred seventy-one million, one hundred seventy-three thousand, eight hundred forty-five".