638393741821 has 8 divisors (see below), whose sum is σ = 696436118784. Its totient is φ = 580352461920.

The previous prime is 638393741813. The next prime is 638393741849. The reversal of 638393741821 is 128147393836.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 638393741821 - 2³ = 638393741813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638393741021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1372276 + ... + 1777618.

It is an arithmetic number, because the mean of its divisors is an integer number (87054514848).

Almost surely, 2^638393741821 is an apocalyptic number.

It is an amenable number.

638393741821 is a deficient number, since it is larger than the sum of its proper divisors (58042376963).

638393741821 is a wasteful number, since it uses less digits than its factorization.

638393741821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 548531.

The product of its digits is 5225472, while the sum is 55.

The spelling of 638393741821 in words is "six hundred thirty-eight billion, three hundred ninety-three million, seven hundred forty-one thousand, eight hundred twenty-one".