644196668 has 6 divisors (see below), whose sum is σ = 1127344176. Its totient is φ = 322098332.

The previous prime is 644196659. The next prime is 644196713. The reversal of 644196668 is 866691446.

644196668 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80524580 + ... + 80524587.

It is an arithmetic number, because the mean of its divisors is an integer number (187890696).

Almost surely, 2^644196668 is an apocalyptic number.

It is an amenable number.

644196668 is a deficient number, since it is larger than the sum of its proper divisors (483147508).

644196668 is a wasteful number, since it uses less digits than its factorization.

644196668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161049171 (or 161049169 counting only the distinct ones).

The product of its digits is 1492992, while the sum is 50.

The square root of 644196668 is about 25381.0296875442. The cubic root of 644196668 is about 863.6534085809.

The spelling of 644196668 in words is "six hundred forty-four million, one hundred ninety-six thousand, six hundred sixty-eight".