638307864 has 80 divisors (see below), whose sum is σ = 1849557600. Its totient is φ = 205426368.

The previous prime is 638307863. The next prime is 638307881. The reversal of 638307864 is 468703836.

638307864 is a `hidden beast` number, since 638 + 3 + 0 + 7 + 8 + 6 + 4 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638307863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1809 + ... + 35775.

It is an arithmetic number, because the mean of its divisors is an integer number (23119470).

Almost surely, 2^638307864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638307864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (924778800).

638307864 is an abundant number, since it is smaller than the sum of its proper divisors (1211249736).

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

638307864 is a wasteful number, since it uses less digits than its factorization.

638307864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34014 (or 34001 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 45.

The square root of 638307864 is about 25264.7553718614. The cubic root of 638307864 is about 861.0137063947.

The spelling of 638307864 in words is "six hundred thirty-eight million, three hundred seven thousand, eight hundred sixty-four".