21100002221 has 2 divisors, whose sum is σ = 21100002222. Its totient is φ = 21100002220.

The previous prime is 21100002181. The next prime is 21100002233. The reversal of 21100002221 is 12220000112.

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., 17728922500 + 3371079721 = 133150^2 + 58061^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100002221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100005221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550001110 + 10550001111.

It is an arithmetic number, because the mean of its divisors is an integer number (10550001111).

Almost surely, 2^21100002221 is an apocalyptic number.

It is an amenable number.

21100002221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100002221 is an equidigital number, since it uses as much as digits as its factorization.

21100002221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21100002221 its reverse (12220000112), we get a palindrome (33320002333).

The spelling of 21100002221 in words is "twenty-one billion, one hundred million, two thousand, two hundred twenty-one".