21021112021 has 32 divisors (see below), whose sum is σ = 26040268800. Its totient is φ = 16524345600.

The previous prime is 21021112003. The next prime is 21021112027. The reversal of 21021112021 is 12021112012.

It is not a de Polignac number, because 21021112021 - 2²⁵ = 20987557589 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a junction number, because it is equal to n+sod(n) for n = 21021111992 and 21021112010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021112027) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14607420 + ... + 14608858.

It is an arithmetic number, because the mean of its divisors is an integer number (813758400).

Almost surely, 2^21021112021 is an apocalyptic number.

It is an amenable number.

21021112021 is a deficient number, since it is larger than the sum of its proper divisors (5019156779).

21021112021 is a wasteful number, since it uses less digits than its factorization.

21021112021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2389.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21021112021 its reverse (12021112012), we get a palindrome (33042224033).

Subtracting from 21021112021 its reverse (12021112012), we obtain a palindrome (9000000009).

The spelling of 21021112021 in words is "twenty-one billion, twenty-one million, one hundred twelve thousand, twenty-one".