168521665 has 16 divisors (see below), whose sum is σ = 218122128. Its totient is φ = 124252416.

The previous prime is 168521653. The next prime is 168521671. The reversal of 168521665 is 566125861.

168521665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 1181569 + 167340096 = 1087^2 + 12936^2 .

It is a cyclic number.

It is not a de Polignac number, because 168521665 - 2¹³ = 168513473 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50179 + ... + 53431.

It is an arithmetic number, because the mean of its divisors is an integer number (13632633).

Almost surely, 2^168521665 is an apocalyptic number.

It is an amenable number.

168521665 is a deficient number, since it is larger than the sum of its proper divisors (49600463).

168521665 is a wasteful number, since it uses less digits than its factorization.

168521665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4068.

The product of its digits is 86400, while the sum is 40.

The square root of 168521665 is about 12981.5894635441. The cubic root of 168521665 is about 552.3553698263.

The spelling of 168521665 in words is "one hundred sixty-eight million, five hundred twenty-one thousand, six hundred sixty-five".