643993378 has 48 divisors (see below), whose sum is σ = 1153059840. Its totient is φ = 268875936.

The previous prime is 643993367. The next prime is 643993393. The reversal of 643993378 is 873399346.

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 23 ways as a sum of consecutive naturals, for example, 733876 + ... + 734752.

It is an arithmetic number, because the mean of its divisors is an integer number (24022080).

Almost surely, 2^643993378 is an apocalyptic number.

643993378 is a deficient number, since it is larger than the sum of its proper divisors (509066462).

643993378 is a wasteful number, since it uses less digits than its factorization.

643993378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1079 (or 1072 counting only the distinct ones).

The product of its digits is 2939328, while the sum is 52.

The square root of 643993378 is about 25377.0246088859. The cubic root of 643993378 is about 863.5625509376.

The spelling of 643993378 in words is "six hundred forty-three million, nine hundred ninety-three thousand, three hundred seventy-eight".