638535680 has 96 divisors (see below), whose sum is σ = 1547320320. Its totient is φ = 252887040.

The previous prime is 638535671. The next prime is 638535697. The reversal of 638535680 is 86535836.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1300235 + ... + 1300725.

It is an arithmetic number, because the mean of its divisors is an integer number (16117920).

Almost surely, 2^638535680 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 638535680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (773660160).

638535680 is an abundant number, since it is smaller than the sum of its proper divisors (908784640).

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

638535680 is a wasteful number, since it uses less digits than its factorization.

638535680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 645 (or 625 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 44.

The square root of 638535680 is about 25269.2635428894. The cubic root of 638535680 is about 861.1161279054.

The spelling of 638535680 in words is "six hundred thirty-eight million, five hundred thirty-five thousand, six hundred eighty".