638390528 has 54 divisors (see below), whose sum is σ = 1352777454. Its totient is φ = 299634688.

The previous prime is 638390521. The next prime is 638390537. The reversal of 638390528 is 825093836.

It can be written as a sum of positive squares in only one way, i.e., 600838144 + 37552384 = 24512^2 + 6128^2 .

It is not an unprimeable number, because it can be changed into a prime (638390521) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1666625 + ... + 1667007.

Almost surely, 2^638390528 is an apocalyptic number.

638390528 is a gapful number since it is divisible by the number (68) 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 638390528, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (676388727).

638390528 is an abundant number, since it is smaller than the sum of its proper divisors (714386926).

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

638390528 is an frugal number, since it uses more digits than its factorization.

638390528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 799 (or 402 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 44.

The square root of 638390528 is about 25266.3912737850. The cubic root of 638390528 is about 861.0508732901.

The spelling of 638390528 in words is "six hundred thirty-eight million, three hundred ninety thousand, five hundred twenty-eight".