638791072 has 24 divisors (see below), whose sum is σ = 1262312100. Its totient is φ = 318203904.

The previous prime is 638791067. The next prime is 638791073. The reversal of 638791072 is 270197836.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 635241616 + 3549456 = 25204^2 + 1884^2 .

It is not an unprimeable number, because it can be changed into a prime (638791073) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28497 + ... + 45712.

Almost surely, 2^638791072 is an apocalyptic number.

It is an amenable number.

638791072 is a deficient number, since it is larger than the sum of its proper divisors (623521028).

638791072 is a wasteful number, since it uses less digits than its factorization.

638791072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74488 (or 74480 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 43.

The square root of 638791072 is about 25274.3164497084. The cubic root of 638791072 is about 861.2309180746.

The spelling of 638791072 in words is "six hundred thirty-eight million, seven hundred ninety-one thousand, seventy-two".