21023231021 has 16 divisors (see below), whose sum is σ = 23266717824. Its totient is φ = 18869868864.

The previous prime is 21023231003. The next prime is 21023231039. The reversal of 21023231021 is 12013232012.

It is an interprime number because it is at equal distance from previous prime (21023231003) and next prime (21023231039).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21023231021 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 (21023231081) 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, 816080 + ... + 841446.

It is an arithmetic number, because the mean of its divisors is an integer number (1454169864).

Almost surely, 2^21023231021 is an apocalyptic number.

It is an amenable number.

21023231021 is a deficient number, since it is larger than the sum of its proper divisors (2243486803).

21023231021 is a wasteful number, since it uses less digits than its factorization.

21023231021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27140.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21023231021 its reverse (12013232012), we get a palindrome (33036463033).

Subtracting from 21023231021 its reverse (12013232012), we obtain a palindrome (9009999009).

The spelling of 21023231021 in words is "twenty-one billion, twenty-three million, two hundred thirty-one thousand, twenty-one".