638581683645 has 24 divisors (see below), whose sum is σ = 1106923723776. Its totient is φ = 340561880928.

The previous prime is 638581683637. The next prime is 638581683673. The reversal of 638581683645 is 546386185836.

638581683645 is a `hidden beast` number, since 6 + 3 + 8 + 581 + 6 + 8 + 3 + 6 + 45 = 666.

It is not a de Polignac number, because 638581683645 - 2³ = 638581683637 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 759444 + ... + 1361586.

It is an arithmetic number, because the mean of its divisors is an integer number (46121821824).

Almost surely, 2^638581683645 is an apocalyptic number.

It is an amenable number.

638581683645 is a deficient number, since it is larger than the sum of its proper divisors (468342040131).

638581683645 is a wasteful number, since it uses less digits than its factorization.

638581683645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 625721 (or 625718 counting only the distinct ones).

The product of its digits is 99532800, while the sum is 63.

The spelling of 638581683645 in words is "six hundred thirty-eight billion, five hundred eighty-one million, six hundred eighty-three thousand, six hundred forty-five".