638710944840 has 256 divisors, whose sum is σ = 2224657612800. Its totient is φ = 162693603072.

The previous prime is 638710944827. The next prime is 638710944923. The reversal of 638710944840 is 48449017836.

638710944840 is a `hidden beast` number, since 6 + 3 + 8 + 71 + 0 + 94 + 484 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 18438817 + ... + 18473423.

It is an arithmetic number, because the mean of its divisors is an integer number (8690068800).

Almost surely, 2^638710944840 is an apocalyptic number.

638710944840 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 638710944840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1112328806400).

638710944840 is an abundant number, since it is smaller than the sum of its proper divisors (1585946667960).

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

638710944840 is a wasteful number, since it uses less digits than its factorization.

638710944840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35393 (or 35383 counting only the distinct ones).

The product of its (nonzero) digits is 4644864, while the sum is 54.

The spelling of 638710944840 in words is "six hundred thirty-eight billion, seven hundred ten million, nine hundred forty-four thousand, eight hundred forty".