21181648221 has 24 divisors (see below), whose sum is σ = 31956724800. Its totient is φ = 13494123456.

The previous prime is 21181648199. The next prime is 21181648259. The reversal of 21181648221 is 12284618112.

21181648221 is a `hidden beast` number, since 2 + 1 + 1 + 8 + 1 + 648 + 2 + 2 + 1 = 666.

It is not a de Polignac number, because 21181648221 - 2¹⁰ = 21181647197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21181648291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 168370 + ... + 265916.

It is an arithmetic number, because the mean of its divisors is an integer number (1331530200).

Almost surely, 2^21181648221 is an apocalyptic number.

It is an amenable number.

21181648221 is a deficient number, since it is larger than the sum of its proper divisors (10775076579).

21181648221 is a wasteful number, since it uses less digits than its factorization.

21181648221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98625 (or 98622 counting only the distinct ones).

The product of its digits is 12288, while the sum is 36.

The spelling of 21181648221 in words is "twenty-one billion, one hundred eighty-one million, six hundred forty-eight thousand, two hundred twenty-one".