638638346840 has 128 divisors (see below), whose sum is σ = 1627965864000. Its totient is φ = 223814535168.

The previous prime is 638638346831. The next prime is 638638346903. The reversal of 638638346840 is 48643836836.

638638346840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (59).

It is a self number, because there is not a number n which added to its sum of digits gives 638638346840.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 530822 + ... + 1248618.

Almost surely, 2^638638346840 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 638638346840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (813982932000).

638638346840 is an abundant number, since it is smaller than the sum of its proper divisors (989327517160).

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

638638346840 is a wasteful number, since it uses less digits than its factorization.

638638346840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 717909 (or 717905 counting only the distinct ones).

The product of its (nonzero) digits is 47775744, while the sum is 59.

The spelling of 638638346840 in words is "six hundred thirty-eight billion, six hundred thirty-eight million, three hundred forty-six thousand, eight hundred forty".