638297856 has 216 divisors, whose sum is σ = 2215041920. Its totient is φ = 172689408.

The previous prime is 638297851. The next prime is 638297867. The reversal of 638297856 is 658792836.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (638297851) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 305391 + ... + 307473.

Almost surely, 2^638297856 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 638297856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1107520960).

638297856 is an abundant number, since it is smaller than the sum of its proper divisors (1576744064).

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

638297856 is a wasteful number, since it uses less digits than its factorization.

638297856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2131 (or 2114 counting only the distinct ones).

The product of its digits is 4354560, while the sum is 54.

The square root of 638297856 is about 25264.5573086092. The cubic root of 638297856 is about 861.0092064396.

The spelling of 638297856 in words is "six hundred thirty-eight million, two hundred ninety-seven thousand, eight hundred fifty-six".