638186885956 has 9 divisors (see below), whose sum is σ = 1116829846461. Its totient is φ = 319092644112.

The previous prime is 638186885951. The next prime is 638186886017. The reversal of 638186885956 is 659588681836.

The square root of 638186885956 is 798866.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 638129368900 + 57517056 = 798830^2 + 7584^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638186885951) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1398016 + ... + 1797448.

Almost surely, 2^638186885956 is an apocalyptic number.

638186885956 is the 798866-th square number.

It is an amenable number.

638186885956 is a deficient number, since it is larger than the sum of its proper divisors (478642960505).

638186885956 is an frugal number, since it uses more digits than its factorization.

638186885956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798870 (or 399435 counting only the distinct ones).

The product of its digits is 597196800, while the sum is 73.

The spelling of 638186885956 in words is "six hundred thirty-eight billion, one hundred eighty-six million, eight hundred eighty-five thousand, nine hundred fifty-six".