21185384704 has 81 divisors (see below), whose sum is σ = 46538139991. Its totient is φ = 9618076160.

The previous prime is 21185384699. The next prime is 21185384707. The reversal of 21185384704 is 40748358112.

The square root of 21185384704 is 145552.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21185384707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 25616739 + ... + 25617565.

Almost surely, 2^21185384704 is an apocalyptic number.

21185384704 is the 145552-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21185384704

21185384704 is an abundant number, since it is smaller than the sum of its proper divisors (25352755287).

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

21185384704 is an frugal number, since it uses more digits than its factorization.

21185384704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1692 (or 840 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 43.

The spelling of 21185384704 in words is "twenty-one billion, one hundred eighty-five million, three hundred eighty-four thousand, seven hundred four".