638862663440 has 80 divisors (see below), whose sum is σ = 1498702670640. Its totient is φ = 253255065600.

The previous prime is 638862663389. The next prime is 638862663451. The reversal of 638862663440 is 44366268836.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 9518734096 + 629343929344 = 97564^2 + 793312^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6538466 + ... + 6635454.

It is an arithmetic number, because the mean of its divisors is an integer number (18733783383).

Almost surely, 2^638862663440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638862663440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (749351335320).

638862663440 is an abundant number, since it is smaller than the sum of its proper divisors (859840007200).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638862663440 is a wasteful number, since it uses less digits than its factorization.

638862663440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97740 (or 97734 counting only the distinct ones).

The product of its (nonzero) digits is 23887872, while the sum is 56.

The spelling of 638862663440 in words is "six hundred thirty-eight billion, eight hundred sixty-two million, six hundred sixty-three thousand, four hundred forty".