665618 has 8 divisors (see below), whose sum is σ = 1057212. Its totient is φ = 313216.

The previous prime is 665617. The next prime is 665629. The reversal of 665618 is 816566.

It can be written as a sum of positive squares in 2 ways, for example, as 552049 + 113569 = 743^2 + 337^2 .

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

It is not an unprimeable number, because it can be changed into a prime (665617) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9755 + ... + 9822.

2⁶⁶⁵⁶¹⁸ is an apocalyptic number.

665618 is a deficient number, since it is larger than the sum of its proper divisors (391594).

665618 is a wasteful number, since it uses less digits than its factorization.

665618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19596.

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

The square root of 665618 is about 815.8541536329. The cubic root of 665618 is about 87.3122177000.

The spelling of 665618 in words is "six hundred sixty-five thousand, six hundred eighteen".