665844818 has 4 divisors (see below), whose sum is σ = 998767230. Its totient is φ = 332922408.

The previous prime is 665844791. The next prime is 665844821. The reversal of 665844818 is 818448566.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 423824569 + 242020249 = 20587^2 + 15557^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166461203 + ... + 166461206.

Almost surely, 2^665844818 is an apocalyptic number.

665844818 is a deficient number, since it is larger than the sum of its proper divisors (332922412).

665844818 is a wasteful number, since it uses less digits than its factorization.

665844818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332922411.

The product of its digits is 1474560, while the sum is 50.

The square root of 665844818 is about 25803.9690357898. The cubic root of 665844818 is about 873.2213416533.

The spelling of 665844818 in words is "six hundred sixty-five million, eight hundred forty-four thousand, eight hundred eighteen".