21111321 has 32 divisors (see below), whose sum is σ = 35712000. Its totient is φ = 10774080.

The previous prime is 21111301. The next prime is 21111373. The reversal of 21111321 is 12311112.

It is not a de Polignac number, because 21111321 - 2⁶ = 21111257 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21111297 and 21111306.

It is not an unprimeable number, because it can be changed into a prime (21111301) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12855 + ... + 14403.

It is an arithmetic number, because the mean of its divisors is an integer number (1116000).

Almost surely, 2^21111321 is an apocalyptic number.

21111321 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21111321 is a deficient number, since it is larger than the sum of its proper divisors (14600679).

21111321 is a wasteful number, since it uses less digits than its factorization.

21111321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1629.

The product of its digits is 12, while the sum is 12.

The square root of 21111321 is about 4594.7057577172. The cubic root of 21111321 is about 276.3790606522.

Adding to 21111321 its reverse (12311112), we get a palindrome (33422433).

The spelling of 21111321 in words is "twenty-one million, one hundred eleven thousand, three hundred twenty-one".