1665345173 has 4 divisors (see below), whose sum is σ = 1710354540. Its totient is φ = 1620335808.

The previous prime is 1665345163. The next prime is 1665345181. The reversal of 1665345173 is 3715435661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3715435661 = 7 ⋅530776523.

It can be written as a sum of positive squares in 2 ways, for example, as 958955089 + 706390084 = 30967^2 + 26578^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665345173 - 2⁸ = 1665344917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1665345173.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665345103) 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, 22504628 + ... + 22504701.

It is an arithmetic number, because the mean of its divisors is an integer number (427588635).

Almost surely, 2^1665345173 is an apocalyptic number.

It is an amenable number.

1665345173 is a deficient number, since it is larger than the sum of its proper divisors (45009367).

1665345173 is an equidigital number, since it uses as much as digits as its factorization.

1665345173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45009366.

The product of its digits is 226800, while the sum is 41.

The square root of 1665345173 is about 40808.6409109639. The cubic root of 1665345173 is about 1185.3176578410.

The spelling of 1665345173 in words is "one billion, six hundred sixty-five million, three hundred forty-five thousand, one hundred seventy-three".