643344666 has 16 divisors (see below), whose sum is σ = 1288782144. Its totient is φ = 214099424.

The previous prime is 643344623. The next prime is 643344701. The reversal of 643344666 is 666443346.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 83190 + ... + 90593.

It is an arithmetic number, because the mean of its divisors is an integer number (80548884).

Almost surely, 2^643344666 is an apocalyptic number.

643344666 is an abundant number, since it is smaller than the sum of its proper divisors (645437478).

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

643344666 is a wasteful number, since it uses less digits than its factorization.

643344666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174405.

The product of its digits is 746496, while the sum is 42.

The square root of 643344666 is about 25364.2399058202. The cubic root of 643344666 is about 863.2724901923.

The spelling of 643344666 in words is "six hundred forty-three million, three hundred forty-four thousand, six hundred sixty-six".