638636216385 has 32 divisors (see below), whose sum is σ = 1027360236672. Its totient is φ = 338759751680.

The previous prime is 638636216353. The next prime is 638636216473. The reversal of 638636216385 is 583612636836.

It is a happy number.

It is not a de Polignac number, because 638636216385 - 2⁵ = 638636216353 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8861617 + ... + 8933393.

It is an arithmetic number, because the mean of its divisors is an integer number (32105007396).

Almost surely, 2^638636216385 is an apocalyptic number.

It is an amenable number.

638636216385 is a deficient number, since it is larger than the sum of its proper divisors (388724020287).

638636216385 is a wasteful number, since it uses less digits than its factorization.

638636216385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74993.

The product of its digits is 22394880, while the sum is 57.

The spelling of 638636216385 in words is "six hundred thirty-eight billion, six hundred thirty-six million, two hundred sixteen thousand, three hundred eighty-five".