18821644864 has 63 divisors (see below), whose sum is σ = 41079604531. Its totient is φ = 8549805440.

The previous prime is 18821644847. The next prime is 18821644909. The reversal of 18821644864 is 46844612881.

The square root of 18821644864 is 137192.

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

It is a Duffinian number.

It is an unprimeable number.

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 8 ways as a sum of consecutive naturals, for example, 12072117 + ... + 12073675.

Almost surely, 2^18821644864 is an apocalyptic number.

18821644864 is the 137192-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18821644864

18821644864 is an abundant number, since it is smaller than the sum of its proper divisors (22257959667).

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

18821644864 is an frugal number, since it uses more digits than its factorization.

18821644864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3152 (or 1572 counting only the distinct ones).

The product of its digits is 2359296, while the sum is 52.

The spelling of 18821644864 in words is "eighteen billion, eight hundred twenty-one million, six hundred forty-four thousand, eight hundred sixty-four".