638313664 has 112 divisors (see below), whose sum is σ = 1441094400. Its totient is φ = 278885376.

The previous prime is 638313661. The next prime is 638313667. The reversal of 638313664 is 466313836.

It is an interprime number because it is at equal distance from previous prime (638313661) and next prime (638313667).

It is not an unprimeable number, because it can be changed into a prime (638313661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 810679 + ... + 811465.

Almost surely, 2^638313664 is an apocalyptic number.

638313664 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638313664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (720547200).

638313664 is an abundant number, since it is smaller than the sum of its proper divisors (802780736).

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

638313664 is a wasteful number, since it uses less digits than its factorization.

638313664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 870 (or 860 counting only the distinct ones).

The product of its digits is 186624, while the sum is 40.

The square root of 638313664 is about 25264.8701560091. The cubic root of 638313664 is about 861.0163142609.

The spelling of 638313664 in words is "six hundred thirty-eight million, three hundred thirteen thousand, six hundred sixty-four".