638605857638 has 16 divisors (see below), whose sum is σ = 1124340815904. Its totient is φ = 266291245440.

The previous prime is 638605857619. The next prime is 638605857653. The reversal of 638605857638 is 836758506836.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 616414403 + ... + 616415438.

It is an arithmetic number, because the mean of its divisors is an integer number (70271300994).

Almost surely, 2^638605857638 is an apocalyptic number.

638605857638 is a deficient number, since it is larger than the sum of its proper divisors (485734958266).

638605857638 is a wasteful number, since it uses less digits than its factorization.

638605857638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1232829887.

The product of its (nonzero) digits is 174182400, while the sum is 65.

The spelling of 638605857638 in words is "six hundred thirty-eight billion, six hundred five million, eight hundred fifty-seven thousand, six hundred thirty-eight".