21112031021 has 16 divisors (see below), whose sum is σ = 21997804800. Its totient is φ = 20243815488.

The previous prime is 21112031011. The next prime is 21112031033. The reversal of 21112031021 is 12013021112.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112031021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21112030987 and 21112031005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112031011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1639235 + ... + 1652063.

It is an arithmetic number, because the mean of its divisors is an integer number (1374862800).

Almost surely, 2^21112031021 is an apocalyptic number.

It is an amenable number.

21112031021 is a deficient number, since it is larger than the sum of its proper divisors (885773779).

21112031021 is a wasteful number, since it uses less digits than its factorization.

21112031021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13508.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21112031021 its reverse (12013021112), we get a palindrome (33125052133).

Subtracting from 21112031021 its reverse (12013021112), we obtain a palindrome (9099009909).

The spelling of 21112031021 in words is "twenty-one billion, one hundred twelve million, thirty-one thousand, twenty-one".