639822556898 has 126 divisors (see below), whose sum is σ = 1201815017379. Its totient is φ = 255419071488.

The previous prime is 639822556787. The next prime is 639822556907. The reversal of 639822556898 is 898655228936.

It can be written as a sum of positive squares in 5 ways, for example, as 470125521649 + 169697035249 = 685657^2 + 411943^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=565607.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 6596108786 + ... + 6596108882.

Almost surely, 2^639822556898 is an apocalyptic number.

639822556898 is a deficient number, since it is larger than the sum of its proper divisors (561992460481).

639822556898 is an frugal number, since it uses more digits than its factorization.

639822556898 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272 (or 123 counting only the distinct ones).

The product of its digits is 447897600, while the sum is 71.

The spelling of 639822556898 in words is "six hundred thirty-nine billion, eight hundred twenty-two million, five hundred fifty-six thousand, eight hundred ninety-eight".