638919648751 has 4 divisors (see below), whose sum is σ = 649748795400. Its totient is φ = 628090502104.

The previous prime is 638919648709. The next prime is 638919648761. The reversal of 638919648751 is 157846919836.

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

It is a cyclic number.

It is not a de Polignac number, because 638919648751 - 2⁷ = 638919648623 is a prime.

It is a Smith number, since the sum of its digits (67) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638919648761) 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 in 3 ways as a sum of consecutive naturals, for example, 5414573236 + ... + 5414573353.

It is an arithmetic number, because the mean of its divisors is an integer number (162437198850).

Almost surely, 2^638919648751 is an apocalyptic number.

638919648751 is a deficient number, since it is larger than the sum of its proper divisors (10829146649).

638919648751 is a wasteful number, since it uses less digits than its factorization.

638919648751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10829146648.

The product of its digits is 78382080, while the sum is 67.

The spelling of 638919648751 in words is "six hundred thirty-eight billion, nine hundred nineteen million, six hundred forty-eight thousand, seven hundred fifty-one".