638636332820 has 48 divisors (see below), whose sum is σ = 1372616813568. Its totient is φ = 249460767360.

The previous prime is 638636332759. The next prime is 638636332847. The reversal of 638636332820 is 28233636836.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4104077 + ... + 4256843.

It is an arithmetic number, because the mean of its divisors is an integer number (28596183616).

Almost surely, 2^638636332820 is an apocalyptic number.

It is an amenable number.

638636332820 is an abundant number, since it is smaller than the sum of its proper divisors (733980480748).

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

638636332820 is a wasteful number, since it uses less digits than its factorization.

638636332820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157680 (or 157678 counting only the distinct ones).

The product of its (nonzero) digits is 4478976, while the sum is 50.

The spelling of 638636332820 in words is "six hundred thirty-eight billion, six hundred thirty-six million, three hundred thirty-two thousand, eight hundred twenty".