21040443031221 has 20 divisors (see below), whose sum is σ = 31432163380332. Its totient is φ = 14026346995968.

The previous prime is 21040443031217. The next prime is 21040443031241. The reversal of 21040443031221 is 12213034404012.

21040443031221 is a `hidden beast` number, since 2 + 1 + 0 + 4 + 0 + 4 + 430 + 3 + 1 + 221 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 10044494183025 + 10995948848196 = 3169305^2 + 3316014^2 .

It is not a de Polignac number, because 21040443031221 - 2² = 21040443031217 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040443031241) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3832156 + ... + 7534341.

Almost surely, 2^{21040443031221} is an apocalyptic number.

It is an amenable number.

21040443031221 is a deficient number, since it is larger than the sum of its proper divisors (10391720349111).

21040443031221 is a wasteful number, since it uses less digits than its factorization.

21040443031221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11389362 (or 11389353 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

Adding to 21040443031221 its reverse (12213034404012), we get a palindrome (33253477435233).

The spelling of 21040443031221 in words is "twenty-one trillion, forty billion, four hundred forty-three million, thirty-one thousand, two hundred twenty-one".