638865858068 has 24 divisors (see below), whose sum is σ = 1136597122920. Its totient is φ = 314126161920.

The previous prime is 638865858011. The next prime is 638865858073. The reversal of 638865858068 is 860858568836.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 132010142224 + 506855715844 = 363332^2 + 711938^2 .

It is a junction number, because it is equal to n+sod(n) for n = 638865857992 and 638865858010.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 811088 + ... + 1391256.

It is an arithmetic number, because the mean of its divisors is an integer number (47358213455).

Almost surely, 2^638865858068 is an apocalyptic number.

It is an amenable number.

638865858068 is a deficient number, since it is larger than the sum of its proper divisors (497731264852).

638865858068 is a wasteful number, since it uses less digits than its factorization.

638865858068 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 584747 (or 584745 counting only the distinct ones).

The product of its (nonzero) digits is 530841600, while the sum is 71.

The spelling of 638865858068 in words is "six hundred thirty-eight billion, eight hundred sixty-five million, eight hundred fifty-eight thousand, sixty-eight".