21021302221 has 2 divisors, whose sum is σ = 21021302222. Its totient is φ = 21021302220.

The previous prime is 21021302191. The next prime is 21021302231. The reversal of 21021302221 is 12220312012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10818080100 + 10203222121 = 104010^2 + 101011^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021302221 - 2³¹ = 18873818573 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21021302195 and 21021302204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21021302231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510651110 + 10510651111.

It is an arithmetic number, because the mean of its divisors is an integer number (10510651111).

Almost surely, 2^21021302221 is an apocalyptic number.

It is an amenable number.

21021302221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021302221 is an equidigital number, since it uses as much as digits as its factorization.

21021302221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21021302221 its reverse (12220312012), we get a palindrome (33241614233).

The spelling of 21021302221 in words is "twenty-one billion, twenty-one million, three hundred two thousand, two hundred twenty-one".