21321121 has 2 divisors, whose sum is σ = 21321122. Its totient is φ = 21321120.

The previous prime is 21321101. The next prime is 21321133. The reversal of 21321121 is 12112312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20802721 + 518400 = 4561^2 + 720^2 .

It is a cyclic number.

It is not a de Polignac number, because 21321121 - 2⁵ = 21321089 is a prime.

It is not a weakly prime, because it can be changed into another prime (21321101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660560 + 10660561.

It is an arithmetic number, because the mean of its divisors is an integer number (10660561).

Almost surely, 2^21321121 is an apocalyptic number.

It is an amenable number.

21321121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321121 is an equidigital number, since it uses as much as digits as its factorization.

21321121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24, while the sum is 13.

The square root of 21321121 is about 4617.4799404004. The cubic root of 21321121 is about 277.2915773948.

Adding to 21321121 its reverse (12112312), we get a palindrome (33433433).

The spelling of 21321121 in words is "twenty-one million, three hundred twenty-one thousand, one hundred twenty-one".