518165521 has 4 divisors (see below), whose sum is σ = 518354100. Its totient is φ = 517976944.

The previous prime is 518165513. The next prime is 518165539. The reversal of 518165521 is 125561815.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125561815 = 5 ⋅25112363.

It can be written as a sum of positive squares in 2 ways, for example, as 332661121 + 185504400 = 18239^2 + 13620^2 .

It is a cyclic number.

It is not a de Polignac number, because 518165521 - 2³ = 518165513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (518165581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90106 + ... + 95683.

It is an arithmetic number, because the mean of its divisors is an integer number (129588525).

Almost surely, 2^518165521 is an apocalyptic number.

It is an amenable number.

518165521 is a deficient number, since it is larger than the sum of its proper divisors (188579).

518165521 is a wasteful number, since it uses less digits than its factorization.

518165521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188578.

The product of its digits is 12000, while the sum is 34.

The square root of 518165521 is about 22763.2493506529. The cubic root of 518165521 is about 803.1984045732.

The spelling of 518165521 in words is "five hundred eighteen million, one hundred sixty-five thousand, five hundred twenty-one".