668165 has 4 divisors (see below), whose sum is σ = 801804. Its totient is φ = 534528.

The previous prime is 668159. The next prime is 668179. The reversal of 668165 is 561866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 561866 = 2 ⋅280933.

It can be written as a sum of positive squares in 2 ways, for example, as 261121 + 407044 = 511^2 + 638^2 .

It is a cyclic number.

It is not a de Polignac number, because 668165 - 2¹⁰ = 667141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66812 + ... + 66821.

It is an arithmetic number, because the mean of its divisors is an integer number (200451).

2⁶⁶⁸¹⁶⁵ is an apocalyptic number.

It is an amenable number.

668165 is a deficient number, since it is larger than the sum of its proper divisors (133639).

668165 is a wasteful number, since it uses less digits than its factorization.

668165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133638.

The product of its digits is 8640, while the sum is 32.

The square root of 668165 is about 817.4136039974. The cubic root of 668165 is about 87.4234432415.

The spelling of 668165 in words is "six hundred sixty-eight thousand, one hundred sixty-five".