638582647685 has 4 divisors (see below), whose sum is σ = 766299177228. Its totient is φ = 510866118144.

The previous prime is 638582647679. The next prime is 638582647727. The reversal of 638582647685 is 586746285836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 215205993409 + 423376654276 = 463903^2 + 650674^2 .

It is a cyclic number.

It is not a de Polignac number, because 638582647685 - 2¹⁰ = 638582646661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63858264764 + ... + 63858264773.

It is an arithmetic number, because the mean of its divisors is an integer number (191574794307).

Almost surely, 2^638582647685 is an apocalyptic number.

It is an amenable number.

638582647685 is a deficient number, since it is larger than the sum of its proper divisors (127716529543).

638582647685 is a wasteful number, since it uses less digits than its factorization.

638582647685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127716529542.

The product of its digits is 464486400, while the sum is 68.

The spelling of 638582647685 in words is "six hundred thirty-eight billion, five hundred eighty-two million, six hundred forty-seven thousand, six hundred eighty-five".