21022221021 has 16 divisors (see below), whose sum is σ = 28245901824. Its totient is φ = 13906966064.

The previous prime is 21022221013. The next prime is 21022221041. The reversal of 21022221021 is 12012222012.

It is a cyclic number.

It is not a de Polignac number, because 21022221021 - 2³ = 21022221013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022221041) 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 15 ways as a sum of consecutive naturals, for example, 258346 + ... + 329828.

It is an arithmetic number, because the mean of its divisors is an integer number (1765368864).

Almost surely, 2^21022221021 is an apocalyptic number.

It is an amenable number.

21022221021 is a deficient number, since it is larger than the sum of its proper divisors (7223680803).

21022221021 is a wasteful number, since it uses less digits than its factorization.

21022221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72240.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21022221021 its reverse (12012222012), we get a palindrome (33034443033).

Subtracting from 21022221021 its reverse (12012222012), we obtain a palindrome (9009999009).

The spelling of 21022221021 in words is "twenty-one billion, twenty-two million, two hundred twenty-one thousand, twenty-one".