638808642 has 12 divisors (see below), whose sum is σ = 1384085430. Its totient is φ = 212936208.

The previous prime is 638808637. The next prime is 638808649. The reversal of 638808642 is 246808836.

It is a happy number.

638808642 is a `hidden beast` number, since 638 + 8 + 0 + 8 + 6 + 4 + 2 = 666.

It can be written as a sum of positive squares in only one way, i.e., 631567161 + 7241481 = 25131^2 + 2691^2 .

It is not an unprimeable number, because it can be changed into a prime (638808649) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17744667 + ... + 17744702.

Almost surely, 2^638808642 is an apocalyptic number.

638808642 is an abundant number, since it is smaller than the sum of its proper divisors (745276788).

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

638808642 is a wasteful number, since it uses less digits than its factorization.

638808642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35489377 (or 35489374 counting only the distinct ones).

The product of its (nonzero) digits is 442368, while the sum is 45.

The square root of 638808642 is about 25274.6640333754. The cubic root of 638808642 is about 861.2388140775.

The spelling of 638808642 in words is "six hundred thirty-eight million, eight hundred eight thousand, six hundred forty-two".