663966778 has 4 divisors (see below), whose sum is σ = 995950170. Its totient is φ = 331983388.

The previous prime is 663966769. The next prime is 663966817. The reversal of 663966778 is 877669366.

663966778 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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., 621155929 + 42810849 = 24923^2 + 6543^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165991693 + ... + 165991696.

Almost surely, 2^663966778 is an apocalyptic number.

663966778 is a deficient number, since it is larger than the sum of its proper divisors (331983392).

663966778 is a wasteful number, since it uses less digits than its factorization.

663966778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331983391.

The product of its digits is 13716864, while the sum is 58.

The square root of 663966778 is about 25767.5528135677. The cubic root of 663966778 is about 872.3995841776.

The spelling of 663966778 in words is "six hundred sixty-three million, nine hundred sixty-six thousand, seven hundred seventy-eight".