638525840 has 40 divisors (see below), whose sum is σ = 1499005248. Its totient is φ = 252927360.

The previous prime is 638525813. The next prime is 638525843. The reversal of 638525840 is 48525836.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (638525843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30506 + ... + 46985.

Almost surely, 2^638525840 is an apocalyptic number.

It is an amenable number.

638525840 is an abundant number, since it is smaller than the sum of its proper divisors (860479408).

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

638525840 is a wasteful number, since it uses less digits than its factorization.

638525840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77607 (or 77601 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 41.

The square root of 638525840 is about 25269.0688391955. The cubic root of 638525840 is about 861.1117045419. Note that the first 3 decimals are identical.

The spelling of 638525840 in words is "six hundred thirty-eight million, five hundred twenty-five thousand, eight hundred forty".