638144768 has 72 divisors (see below), whose sum is σ = 1349040000. Its totient is φ = 300754944.

The previous prime is 638144761. The next prime is 638144777. The reversal of 638144768 is 867441836.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (638144761) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 318233 + ... + 320231.

Almost surely, 2^638144768 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 638144768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (674520000).

638144768 is an abundant number, since it is smaller than the sum of its proper divisors (710895232).

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

638144768 is a wasteful number, since it uses less digits than its factorization.

638144768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2087 (or 2073 counting only the distinct ones).

The product of its digits is 774144, while the sum is 47.

The square root of 638144768 is about 25261.5274280872. The cubic root of 638144768 is about 860.9403667304.

The spelling of 638144768 in words is "six hundred thirty-eight million, one hundred forty-four thousand, seven hundred sixty-eight".