21312213120221 has 2 divisors, whose sum is σ = 21312213120222. Its totient is φ = 21312213120220.

The previous prime is 21312213120139. The next prime is 21312213120229. The reversal of 21312213120221 is 12202131221312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21288866808196 + 23346312025 = 4613986^2 + 152795^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21312213120221 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 (21312213120229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656106560110 + 10656106560111.

It is an arithmetic number, because the mean of its divisors is an integer number (10656106560111).

Almost surely, 2^{21312213120221} is an apocalyptic number.

It is an amenable number.

21312213120221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312213120221 is an equidigital number, since it uses as much as digits as its factorization.

21312213120221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 23.

Adding to 21312213120221 its reverse (12202131221312), we get a palindrome (33514344341533).

The spelling of 21312213120221 in words is "twenty-one trillion, three hundred twelve billion, two hundred thirteen million, one hundred twenty thousand, two hundred twenty-one".