638778888 has 96 divisors (see below), whose sum is σ = 1893528000. Its totient is φ = 192931200.

The previous prime is 638778887. The next prime is 638778919. The reversal of 638778888 is 888877836.

It is not an unprimeable number, because it can be changed into a prime (638778887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 275253 + ... + 277563.

It is an arithmetic number, because the mean of its divisors is an integer number (19724250).

Almost surely, 2^638778888 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 638778888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (946764000).

638778888 is an abundant number, since it is smaller than the sum of its proper divisors (1254749112).

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

638778888 is a wasteful number, since it uses less digits than its factorization.

638778888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2683 (or 2676 counting only the distinct ones).

The product of its digits is 28901376, while the sum is 63.

The square root of 638778888 is about 25274.0754133559. The cubic root of 638778888 is about 861.2254424689.

The spelling of 638778888 in words is "six hundred thirty-eight million, seven hundred seventy-eight thousand, eight hundred eighty-eight".