21021111021 has 8 divisors (see below), whose sum is σ = 28679965600. Its totient is φ = 13688165232.

The previous prime is 21021110989. The next prime is 21021111029. The reversal of 21021111021 is 12011112012.

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

It is not a de Polignac number, because 21021111021 - 2⁵ = 21021110989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021110988 and 21021111006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021111029) 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, 81477046 + ... + 81477303.

It is an arithmetic number, because the mean of its divisors is an integer number (3584995700).

Almost surely, 2^21021111021 is an apocalyptic number.

It is an amenable number.

21021111021 is a deficient number, since it is larger than the sum of its proper divisors (7658854579).

21021111021 is a wasteful number, since it uses less digits than its factorization.

21021111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162954395.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21021111021 its reverse (12011112012), we get a palindrome (33032223033).

Subtracting from 21021111021 its reverse (12011112012), we obtain a palindrome (9009999009).

The spelling of 21021111021 in words is "twenty-one billion, twenty-one million, one hundred eleven thousand, twenty-one".