18721821304384 has 63 divisors (see below), whose sum is σ = 40836352696321. Its totient is φ = 8509745699840.

The previous prime is 18721821304343. The next prime is 18721821304409. The reversal of 18721821304384 is 48340312812781.

It is a happy number.

The square root of 18721821304384 is 4326872.

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., 12839838225984 + 5881983078400 = 3583272^2 + 2425280^2 .

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, 380740152 + ... + 380789320.

Almost surely, 2^{18721821304384} is an apocalyptic number.

18721821304384 is the 4326872-nd square number.

It is an amenable number.

18721821304384 is an abundant number, since it is smaller than the sum of its proper divisors (22114531391937).

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

18721821304384 is an frugal number, since it uses more digits than its factorization.

18721821304384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98372 (or 49182 counting only the distinct ones).

The product of its (nonzero) digits is 2064384, while the sum is 52.

The spelling of 18721821304384 in words is "eighteen trillion, seven hundred twenty-one billion, eight hundred twenty-one million, three hundred four thousand, three hundred eighty-four".