639431985 has 16 divisors (see below), whose sum is σ = 1076938560. Its totient is φ = 323081280.

The previous prime is 639431963. The next prime is 639432011. The reversal of 639431985 is 589134936.

639431985 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 639431985 - 2⁵ = 639431953 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1121526 + ... + 1122095.

It is an arithmetic number, because the mean of its divisors is an integer number (67308660).

Almost surely, 2^639431985 is an apocalyptic number.

It is an amenable number.

639431985 is a deficient number, since it is larger than the sum of its proper divisors (437506575).

639431985 is a wasteful number, since it uses less digits than its factorization.

639431985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2243648.

The product of its digits is 699840, while the sum is 48.

The square root of 639431985 is about 25286.9924071646. The cubic root of 639431985 is about 861.5188523805.

The spelling of 639431985 in words is "six hundred thirty-nine million, four hundred thirty-one thousand, nine hundred eighty-five".