665606 has 4 divisors (see below), whose sum is σ = 998412. Its totient is φ = 332802.

The previous prime is 665603. The next prime is 665617. The reversal of 665606 is 606566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 606566 = 2 ⋅303283.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166400 + ... + 166403.

It is an arithmetic number, because the mean of its divisors is an integer number (249603).

2⁶⁶⁵⁶⁰⁶ is an apocalyptic number.

665606 is a deficient number, since it is larger than the sum of its proper divisors (332806).

665606 is a wasteful number, since it uses less digits than its factorization.

665606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332805.

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 665606 is about 815.8467993441. The cubic root of 665606 is about 87.3116929982.

It can be divided in two parts, 66560 and 6, that added together give a palindrome (66566).

The spelling of 665606 in words is "six hundred sixty-five thousand, six hundred six".