638161836 has 96 divisors (see below), whose sum is σ = 1636060608. Its totient is φ = 192430080.

The previous prime is 638161819. The next prime is 638161837.

638161836 is nontrivially palindromic in base 10.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (638161837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2738776 + ... + 2739008.

It is an arithmetic number, because the mean of its divisors is an integer number (17042298).

Almost surely, 2^638161836 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 638161836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (818030304).

638161836 is an abundant number, since it is smaller than the sum of its proper divisors (997898772).

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

638161836 is a wasteful number, since it uses less digits than its factorization.

638161836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 531 (or 529 counting only the distinct ones).

The product of its digits is 124416, while the sum is 42.

The square root of 638161836 is about 25261.8652517980. The cubic root of 638161836 is about 860.9480423132.

The spelling of 638161836 in words is "six hundred thirty-eight million, one hundred sixty-one thousand, eight hundred thirty-six".