21112320221 has 2 divisors, whose sum is σ = 21112320222. Its totient is φ = 21112320220.

The previous prime is 21112320191. The next prime is 21112320223. The reversal of 21112320221 is 12202321112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17321455321 + 3790864900 = 131611^2 + 61570^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112320221 is a prime.

It is a super-2 number, since 2×21112320221² (a number of 21 digits) contains 22 as substring.

Together with 21112320223, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21112320221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21112320223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556160110 + 10556160111.

It is an arithmetic number, because the mean of its divisors is an integer number (10556160111).

Almost surely, 2^21112320221 is an apocalyptic number.

It is an amenable number.

21112320221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112320221 is an equidigital number, since it uses as much as digits as its factorization.

21112320221 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 17.

Adding to 21112320221 its reverse (12202321112), we get a palindrome (33314641333).

The spelling of 21112320221 in words is "twenty-one billion, one hundred twelve million, three hundred twenty thousand, two hundred twenty-one".