638111965680 has 480 divisors, whose sum is σ = 2513242892160. Its totient is φ = 142048788480.

The previous prime is 638111965669. The next prime is 638111965703. The reversal of 638111965680 is 86569111836.

638111965680 is a `hidden beast` number, since 63 + 8 + 1 + 1 + 19 + 6 + 568 + 0 = 666.

638111965680 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 134933556 + ... + 134938284.

It is an arithmetic number, because the mean of its divisors is an integer number (5235922692).

Almost surely, 2^638111965680 is an apocalyptic number.

638111965680 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638111965680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1256621446080).

638111965680 is an abundant number, since it is smaller than the sum of its proper divisors (1875130926480).

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

638111965680 is a wasteful number, since it uses less digits than its factorization.

638111965680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5449 (or 5440 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 54.

The spelling of 638111965680 in words is "six hundred thirty-eight billion, one hundred eleven million, nine hundred sixty-five thousand, six hundred eighty".