639856378 has 16 divisors (see below), whose sum is σ = 1106962560. Its totient is φ = 271707696.

The previous prime is 639856367. The next prime is 639856381. The reversal of 639856378 is 873658936.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 208126 + ... + 211177.

It is an arithmetic number, because the mean of its divisors is an integer number (69185160).

Almost surely, 2^639856378 is an apocalyptic number.

639856378 is a deficient number, since it is larger than the sum of its proper divisors (467106182).

639856378 is a wasteful number, since it uses less digits than its factorization.

639856378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 419421.

The product of its digits is 6531840, while the sum is 55.

The square root of 639856378 is about 25295.3825430650. The cubic root of 639856378 is about 861.7094078111.

The spelling of 639856378 in words is "six hundred thirty-nine million, eight hundred fifty-six thousand, three hundred seventy-eight".