638390536 has 64 divisors (see below), whose sum is σ = 1394426880. Its totient is φ = 268349760.

The previous prime is 638390521. The next prime is 638390537. The reversal of 638390536 is 635093836.

It is a junction number, because it is equal to n+sod(n) for n = 638390492 and 638390501.

It is not an unprimeable number, because it can be changed into a prime (638390537) 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, 1220371 + ... + 1220893.

It is an arithmetic number, because the mean of its divisors is an integer number (21787920).

Almost surely, 2^638390536 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 638390536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (697213440).

638390536 is an abundant number, since it is smaller than the sum of its proper divisors (756036344).

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

638390536 is a wasteful number, since it uses less digits than its factorization.

638390536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 914 (or 910 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 43.

The square root of 638390536 is about 25266.3914320981. The cubic root of 638390536 is about 861.0508768868.

The spelling of 638390536 in words is "six hundred thirty-eight million, three hundred ninety thousand, five hundred thirty-six".