665642 has 8 divisors (see below), whose sum is σ = 1003332. Its totient is φ = 331200.

The previous prime is 665633. The next prime is 665659. The reversal of 665642 is 246566.

665642 is nontrivially palindromic in base 16.

It can be written as a sum of positive squares in 2 ways, for example, as 657721 + 7921 = 811^2 + 89^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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, 209 + ... + 1172.

2⁶⁶⁵⁶⁴² is an apocalyptic number.

665642 is a deficient number, since it is larger than the sum of its proper divisors (337690).

665642 is a wasteful number, since it uses less digits than its factorization.

665642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1624.

The product of its digits is 8640, while the sum is 29.

The square root of 665642 is about 815.8688620115. The cubic root of 665642 is about 87.3132670847.

It can be divided in two parts, 66564 and 2, that added together give a palindrome (66566).

The spelling of 665642 in words is "six hundred sixty-five thousand, six hundred forty-two".