665811618 has 8 divisors (see below), whose sum is σ = 1331623248. Its totient is φ = 221937204.

The previous prime is 665811617. The next prime is 665811631. The reversal of 665811618 is 816118566.

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

665811618 is an admirable number.

It is a super-2 number, since 2×665811618² = 886610221327555848, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 665811618.

It is not an unprimeable number, because it can be changed into a prime (665811617) 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, 55484296 + ... + 55484307.

It is an arithmetic number, because the mean of its divisors is an integer number (166452906).

Almost surely, 2^665811618 is an apocalyptic number.

665811618 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665811618 is a wasteful number, since it uses less digits than its factorization.

665811618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110968608.

The product of its digits is 69120, while the sum is 42.

The square root of 665811618 is about 25803.3257158840. The cubic root of 665811618 is about 873.2068280462.

The spelling of 665811618 in words is "six hundred sixty-five million, eight hundred eleven thousand, six hundred eighteen".