638556668 has 12 divisors (see below), whose sum is σ = 1119414912. Its totient is φ = 318723840.

The previous prime is 638556661. The next prime is 638556671. The reversal of 638556668 is 866655836.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638556661) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 136028 + ... + 140643.

It is an arithmetic number, because the mean of its divisors is an integer number (93284576).

Almost surely, 2^638556668 is an apocalyptic number.

It is an amenable number.

638556668 is a deficient number, since it is larger than the sum of its proper divisors (480858244).

638556668 is a wasteful number, since it uses less digits than its factorization.

638556668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277252 (or 277250 counting only the distinct ones).

The product of its digits is 6220800, while the sum is 53.

The square root of 638556668 is about 25269.6788266096. The cubic root of 638556668 is about 861.1255624642.

The spelling of 638556668 in words is "six hundred thirty-eight million, five hundred fifty-six thousand, six hundred sixty-eight".