638681318377 has 4 divisors (see below), whose sum is σ = 638705191680. Its totient is φ = 638657445076.

The previous prime is 638681318357. The next prime is 638681318399. The reversal of 638681318377 is 773813186836.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638681318377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638681318357) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11896477 + ... + 11950042.

It is an arithmetic number, because the mean of its divisors is an integer number (159676297920).

Almost surely, 2^638681318377 is an apocalyptic number.

It is an amenable number.

638681318377 is a deficient number, since it is larger than the sum of its proper divisors (23873303).

638681318377 is a wasteful number, since it uses less digits than its factorization.

638681318377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23873302.

The product of its digits is 24385536, while the sum is 61.

The spelling of 638681318377 in words is "six hundred thirty-eight billion, six hundred eighty-one million, three hundred eighteen thousand, three hundred seventy-seven".