21121323321 has 16 divisors (see below), whose sum is σ = 32187208064. Its totient is φ = 12068452224.

The previous prime is 21121323319. The next prime is 21121323359. The reversal of 21121323321 is 12332312112.

It is not a de Polignac number, because 21121323321 - 2¹ = 21121323319 is a prime.

It is a super-2 number, since 2×21121323321² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121323121) 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, 360351 + ... + 414843.

It is an arithmetic number, because the mean of its divisors is an integer number (2011700504).

Almost surely, 2^21121323321 is an apocalyptic number.

21121323321 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21121323321 is a deficient number, since it is larger than the sum of its proper divisors (11065884743).

21121323321 is a wasteful number, since it uses less digits than its factorization.

21121323321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72960.

The product of its digits is 432, while the sum is 21.

Adding to 21121323321 its reverse (12332312112), we get a palindrome (33453635433).

The spelling of 21121323321 in words is "twenty-one billion, one hundred twenty-one million, three hundred twenty-three thousand, three hundred twenty-one".