21311302320221 has 2 divisors, whose sum is σ = 21311302320222. Its totient is φ = 21311302320220.

The previous prime is 21311302320197. The next prime is 21311302320359. The reversal of 21311302320221 is 12202320311312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21174823795321 + 136478524900 = 4601611^2 + 369430^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311302320221 - 2⁴² = 16913255809117 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21311302320521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655651160110 + 10655651160111.

It is an arithmetic number, because the mean of its divisors is an integer number (10655651160111).

Almost surely, 2^{21311302320221} is an apocalyptic number.

It is an amenable number.

21311302320221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311302320221 is an equidigital number, since it uses as much as digits as its factorization.

21311302320221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

Adding to 21311302320221 its reverse (12202320311312), we get a palindrome (33513622631533).

The spelling of 21311302320221 in words is "twenty-one trillion, three hundred eleven billion, three hundred two million, three hundred twenty thousand, two hundred twenty-one".