638564394571 has 16 divisors (see below), whose sum is σ = 656765192160. Its totient is φ = 620490481920.

The previous prime is 638564394437. The next prime is 638564394619. The reversal of 638564394571 is 175493465836.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 638564394571 - 2¹⁷ = 638564263499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638564394271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32209900 + ... + 32229718.

It is an arithmetic number, because the mean of its divisors is an integer number (41047824510).

Almost surely, 2^638564394571 is an apocalyptic number.

638564394571 is a deficient number, since it is larger than the sum of its proper divisors (18200797589).

638564394571 is a wasteful number, since it uses less digits than its factorization.

638564394571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22974.

The product of its digits is 65318400, while the sum is 61.

The spelling of 638564394571 in words is "six hundred thirty-eight billion, five hundred sixty-four million, three hundred ninety-four thousand, five hundred seventy-one".