638392656 has 80 divisors (see below), whose sum is σ = 1803456000. Its totient is φ = 192984960.

The previous prime is 638392637. The next prime is 638392679. The reversal of 638392656 is 656293836.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 262261 + ... + 264683.

It is an arithmetic number, because the mean of its divisors is an integer number (22543200).

Almost surely, 2^638392656 is an apocalyptic number.

638392656 is a gapful number since it is divisible by the number (66) 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 638392656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (901728000).

638392656 is an abundant number, since it is smaller than the sum of its proper divisors (1165063344).

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

638392656 is a wasteful number, since it uses less digits than its factorization.

638392656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2944 (or 2938 counting only the distinct ones).

The product of its digits is 1399680, while the sum is 48.

The square root of 638392656 is about 25266.4333850269. The cubic root of 638392656 is about 861.0518300264.

The spelling of 638392656 in words is "six hundred thirty-eight million, three hundred ninety-two thousand, six hundred fifty-six".