21321132221 has 2 divisors, whose sum is σ = 21321132222. Its totient is φ = 21321132220.

The previous prime is 21321132211. The next prime is 21321132241. The reversal of 21321132221 is 12223112312.

It is an a-pointer prime, because the next prime (21321132241) can be obtained adding 21321132221 to its sum of digits (20).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11293312900 + 10027819321 = 106270^2 + 100139^2 .

It is a cyclic number.

It is not a de Polignac number, because 21321132221 - 2¹⁰ = 21321131197 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21321132193 and 21321132202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21321132211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660566110 + 10660566111.

It is an arithmetic number, because the mean of its divisors is an integer number (10660566111).

Almost surely, 2^21321132221 is an apocalyptic number.

It is an amenable number.

21321132221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321132221 is an equidigital number, since it uses as much as digits as its factorization.

21321132221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 20.

Adding to 21321132221 its reverse (12223112312), we get a palindrome (33544244533).

The spelling of 21321132221 in words is "twenty-one billion, three hundred twenty-one million, one hundred thirty-two thousand, two hundred twenty-one".