638611887628 has 24 divisors (see below), whose sum is σ = 1312950315600. Its totient is φ = 267949043520.

The previous prime is 638611887587. The next prime is 638611887629. The reversal of 638611887628 is 826788116836.

It is a self number, because there is not a number n which added to its sum of digits gives 638611887628.

It is not an unprimeable number, because it can be changed into a prime (638611887629) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 558226603 + ... + 558227746.

It is an arithmetic number, because the mean of its divisors is an integer number (54706263150).

Almost surely, 2^638611887628 is an apocalyptic number.

It is an amenable number.

638611887628 is an abundant number, since it is smaller than the sum of its proper divisors (674338427972).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638611887628 is a wasteful number, since it uses less digits than its factorization.

638611887628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1116454377 (or 1116454375 counting only the distinct ones).

The product of its digits is 37158912, while the sum is 64.

It can be divided in two parts, 6386118 and 87628, that added together give a palindrome (6473746).

The spelling of 638611887628 in words is "six hundred thirty-eight billion, six hundred eleven million, eight hundred eighty-seven thousand, six hundred twenty-eight".