21320331021 has 24 divisors (see below), whose sum is σ = 33636622656. Its totient is φ = 12905663040.

The previous prime is 21320331007. The next prime is 21320331047. The reversal of 21320331021 is 12013302312.

It is not a de Polignac number, because 21320331021 - 2¹⁸ = 21320068877 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21320330985 and 21320331003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320331421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 49360 + ... + 212313.

It is an arithmetic number, because the mean of its divisors is an integer number (1401525944).

Almost surely, 2^21320331021 is an apocalyptic number.

It is an amenable number.

21320331021 is a deficient number, since it is larger than the sum of its proper divisors (12316291635).

21320331021 is a wasteful number, since it uses less digits than its factorization.

21320331021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262513 (or 262510 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

Adding to 21320331021 its reverse (12013302312), we get a palindrome (33333633333).

The spelling of 21320331021 in words is "twenty-one billion, three hundred twenty million, three hundred thirty-one thousand, twenty-one".