638613888 has 128 divisors (see below), whose sum is σ = 1910615040. Its totient is φ = 187238400.

The previous prime is 638613853. The next prime is 638613889. The reversal of 638613888 is 888316836.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-3 number, since 3×638613888³ (a number of 27 digits) contains 333 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 638613888.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638613889) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 128506 + ... + 133382.

It is an arithmetic number, because the mean of its divisors is an integer number (14926680).

Almost surely, 2^638613888 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 638613888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (955307520).

638613888 is an abundant number, since it is smaller than the sum of its proper divisors (1272001152).

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

638613888 is a wasteful number, since it uses less digits than its factorization.

638613888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4936 (or 4924 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 51.

The square root of 638613888 is about 25270.8109881737. The cubic root of 638613888 is about 861.1512830387.

The spelling of 638613888 in words is "six hundred thirty-eight million, six hundred thirteen thousand, eight hundred eighty-eight".