639681428 has 48 divisors (see below), whose sum is σ = 1194904704. Its totient is φ = 298995840.

The previous prime is 639681377. The next prime is 639681431. The reversal of 639681428 is 824186936.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 967418 + ... + 968078.

It is an arithmetic number, because the mean of its divisors is an integer number (24893848).

Almost surely, 2^639681428 is an apocalyptic number.

It is an amenable number.

639681428 is a deficient number, since it is larger than the sum of its proper divisors (555223276).

639681428 is a wasteful number, since it uses less digits than its factorization.

639681428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 912 (or 910 counting only the distinct ones).

The product of its digits is 497664, while the sum is 47.

The square root of 639681428 is about 25291.9241656304. The cubic root of 639681428 is about 861.6308642462.

The spelling of 639681428 in words is "six hundred thirty-nine million, six hundred eighty-one thousand, four hundred twenty-eight".