21044421021 has 48 divisors (see below), whose sum is σ = 32582729088. Its totient is φ = 11987268480.

The previous prime is 21044421019. The next prime is 21044421031. The reversal of 21044421021 is 12012444012.

It is not a de Polignac number, because 21044421021 - 2¹ = 21044421019 is a prime.

It is a super-2 number, since 2×21044421021² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21044421011) 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 47 ways as a sum of consecutive naturals, for example, 849811 + ... + 874223.

It is an arithmetic number, because the mean of its divisors is an integer number (678806856).

Almost surely, 2^21044421021 is an apocalyptic number.

It is an amenable number.

21044421021 is a deficient number, since it is larger than the sum of its proper divisors (11538308067).

21044421021 is a wasteful number, since it uses less digits than its factorization.

21044421021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24514 (or 24483 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

Adding to 21044421021 its reverse (12012444012), we get a palindrome (33056865033).

The spelling of 21044421021 in words is "twenty-one billion, forty-four million, four hundred twenty-one thousand, twenty-one".