21216212423213 has 2 divisors, whose sum is σ = 21216212423214. Its totient is φ = 21216212423212.

The previous prime is 21216212423191. The next prime is 21216212423227. The reversal of 21216212423213 is 31232421261212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14407019652964 + 6809192770249 = 3795658^2 + 2609443^2 .

It is a cyclic number.

It is not a de Polignac number, because 21216212423213 - 2⁶ = 21216212423149 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21216212423213.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21216212423713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10608106211606 + 10608106211607.

It is an arithmetic number, because the mean of its divisors is an integer number (10608106211607).

Almost surely, 2^{21216212423213} is an apocalyptic number.

It is an amenable number.

21216212423213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21216212423213 is an equidigital number, since it uses as much as digits as its factorization.

21216212423213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 32.

Adding to 21216212423213 its reverse (31232421261212), we get a palindrome (52448633684425).

The spelling of 21216212423213 in words is "twenty-one trillion, two hundred sixteen billion, two hundred twelve million, four hundred twenty-three thousand, two hundred thirteen".