638825554818 has 128 divisors (see below), whose sum is σ = 1631102054400. Its totient is φ = 183290817600.

The previous prime is 638825554811. The next prime is 638825554849. The reversal of 638825554818 is 818455528836.

It is a happy number.

638825554818 is a `hidden beast` number, since 6 + 3 + 8 + 82 + 5 + 5 + 548 + 1 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (638825554811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 21100980 + ... + 21131232.

It is an arithmetic number, because the mean of its divisors is an integer number (12742984800).

Almost surely, 2^638825554818 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638825554818, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (815551027200).

638825554818 is an abundant number, since it is smaller than the sum of its proper divisors (992276499582).

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

638825554818 is a wasteful number, since it uses less digits than its factorization.

638825554818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32165 (or 32159 counting only the distinct ones).

The product of its digits is 73728000, while the sum is 63.

The spelling of 638825554818 in words is "six hundred thirty-eight billion, eight hundred twenty-five million, five hundred fifty-four thousand, eight hundred eighteen".