638447985 has 24 divisors (see below), whose sum is σ = 1264735680. Its totient is φ = 291861792.

The previous prime is 638447959. The next prime is 638447993. The reversal of 638447985 is 589744836.

638447985 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 638447985 - 2⁹ = 638447473 is a prime.

It is a zygodrome in base 3.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1013095 + ... + 1013724.

It is an arithmetic number, because the mean of its divisors is an integer number (52697320).

Almost surely, 2^638447985 is an apocalyptic number.

It is an amenable number.

638447985 is a deficient number, since it is larger than the sum of its proper divisors (626287695).

638447985 is a wasteful number, since it uses less digits than its factorization.

638447985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2026837 (or 2026834 counting only the distinct ones).

The product of its digits is 5806080, while the sum is 54.

The square root of 638447985 is about 25267.5282724686. The cubic root of 638447985 is about 861.0767048742.

The spelling of 638447985 in words is "six hundred thirty-eight million, four hundred forty-seven thousand, nine hundred eighty-five".