21012221021 has 8 divisors (see below), whose sum is σ = 23919050304. Its totient is φ = 18271496320.

The previous prime is 21012220969. The next prime is 21012221047. The reversal of 21012221021 is 12012221012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21012221021 - 2²² = 21008026717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012220987 and 21012221005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012221921) 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 7 ways as a sum of consecutive naturals, for example, 41525876 + ... + 41526381.

It is an arithmetic number, because the mean of its divisors is an integer number (2989881288).

Almost surely, 2^21012221021 is an apocalyptic number.

It is an amenable number.

21012221021 is a deficient number, since it is larger than the sum of its proper divisors (2906829283).

21012221021 is a wasteful number, since it uses less digits than its factorization.

21012221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83052291.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21012221021 its reverse (12012221012), we get a palindrome (33024442033).

Subtracting from 21012221021 its reverse (12012221012), we obtain a palindrome (9000000009).

The spelling of 21012221021 in words is "twenty-one billion, twelve million, two hundred twenty-one thousand, twenty-one".