638256768 has 64 divisors (see below), whose sum is σ = 1750091520. Its totient is φ = 205885440.

The previous prime is 638256763. The next prime is 638256791. The reversal of 638256768 is 867652836.

It is a tau number, because it is divible by the number of its divisors (64).

It is a self number, because there is not a number n which added to its sum of digits gives 638256768.

It is not an unprimeable number, because it can be changed into a prime (638256763) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14905 + ... + 38712.

It is an arithmetic number, because the mean of its divisors is an integer number (27345180).

Almost surely, 2^638256768 is an apocalyptic number.

It is an amenable number.

638256768 is an abundant number, since it is smaller than the sum of its proper divisors (1111834752).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

638256768 is a wasteful number, since it uses less digits than its factorization.

638256768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53665 (or 53653 counting only the distinct ones).

The product of its digits is 2903040, while the sum is 51.

The square root of 638256768 is about 25263.7441405663. The cubic root of 638256768 is about 860.9907313108.

The spelling of 638256768 in words is "six hundred thirty-eight million, two hundred fifty-six thousand, seven hundred sixty-eight".