21111122021221 has 8 divisors (see below), whose sum is σ = 21458610561024. Its totient is φ = 20763678790320.

The previous prime is 21111122021153. The next prime is 21111122021287. The reversal of 21111122021221 is 12212022111112.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111122021221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111122021291) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10387045 + ... + 12252058.

It is an arithmetic number, because the mean of its divisors is an integer number (2682326320128).

Almost surely, 2^{21111122021221} is an apocalyptic number.

It is an amenable number.

21111122021221 is a deficient number, since it is larger than the sum of its proper divisors (347488539803).

21111122021221 is a wasteful number, since it uses less digits than its factorization.

21111122021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22654451.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21111122021221 its reverse (12212022111112), we get a palindrome (33323144132333).

The spelling of 21111122021221 in words is "twenty-one trillion, one hundred eleven billion, one hundred twenty-two million, twenty-one thousand, two hundred twenty-one".