638611556078 has 4 divisors (see below), whose sum is σ = 957917334120. Its totient is φ = 319305778038.

The previous prime is 638611556071. The next prime is 638611556129. The reversal of 638611556078 is 870655116836.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638611556071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159652889018 + ... + 159652889021.

It is an arithmetic number, because the mean of its divisors is an integer number (239479333530).

Almost surely, 2^638611556078 is an apocalyptic number.

638611556078 is a deficient number, since it is larger than the sum of its proper divisors (319305778042).

638611556078 is a wasteful number, since it uses less digits than its factorization.

638611556078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319305778041.

The product of its (nonzero) digits is 7257600, while the sum is 56.

The spelling of 638611556078 in words is "six hundred thirty-eight billion, six hundred eleven million, five hundred fifty-six thousand, seventy-eight".