663841666 has 4 divisors (see below), whose sum is σ = 995762502. Its totient is φ = 331920832.

The previous prime is 663841649. The next prime is 663841699. The reversal of 663841666 is 666148366.

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., 656845641 + 6996025 = 25629^2 + 2645^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165960415 + ... + 165960418.

Almost surely, 2^663841666 is an apocalyptic number.

663841666 is a deficient number, since it is larger than the sum of its proper divisors (331920836).

663841666 is a wasteful number, since it uses less digits than its factorization.

663841666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331920835.

The product of its digits is 746496, while the sum is 46.

The square root of 663841666 is about 25765.1249948453. The cubic root of 663841666 is about 872.3447849935.

The spelling of 663841666 in words is "six hundred sixty-three million, eight hundred forty-one thousand, six hundred sixty-six".