638668785 has 32 divisors (see below), whose sum is σ = 1049518080. Its totient is φ = 331531200.

The previous prime is 638668783. The next prime is 638668837. The reversal of 638668785 is 587866836.

It is a happy number.

638668785 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 638668785 - 2¹ = 638668783 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (638668781) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 80340 + ... + 87930.

It is an arithmetic number, because the mean of its divisors is an integer number (32797440).

Almost surely, 2^638668785 is an apocalyptic number.

It is an amenable number.

638668785 is a deficient number, since it is larger than the sum of its proper divisors (410849295).

638668785 is a wasteful number, since it uses less digits than its factorization.

638668785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7749.

The product of its digits is 11612160, while the sum is 57.

The square root of 638668785 is about 25271.8971389170. The cubic root of 638668785 is about 861.1759579731.

The spelling of 638668785 in words is "six hundred thirty-eight million, six hundred sixty-eight thousand, seven hundred eighty-five".