663819866 has 4 divisors (see below), whose sum is σ = 995729802. Its totient is φ = 331909932.

The previous prime is 663819851. The next prime is 663819901. The reversal of 663819866 is 668918366.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 668918366 = 2 ⋅334459183.

It can be written as a sum of positive squares in only one way, i.e., 629257225 + 34562641 = 25085^2 + 5879^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165954965 + ... + 165954968.

Almost surely, 2^663819866 is an apocalyptic number.

663819866 is a deficient number, since it is larger than the sum of its proper divisors (331909936).

663819866 is a wasteful number, since it uses less digits than its factorization.

663819866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331909935.

The product of its digits is 2239488, while the sum is 53.

The square root of 663819866 is about 25764.7019388931. The cubic root of 663819866 is about 872.3352358669.

The spelling of 663819866 in words is "six hundred sixty-three million, eight hundred nineteen thousand, eight hundred sixty-six".