21213311331217 has 2 divisors, whose sum is σ = 21213311331218. Its totient is φ = 21213311331216.

The previous prime is 21213311331181. The next prime is 21213311331283. The reversal of 21213311331217 is 71213311331212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17010089700241 + 4203221630976 = 4124329^2 + 2050176^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213311331217 is a prime.

It is not a weakly prime, because it can be changed into another prime (21213311332217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606655665608 + 10606655665609.

It is an arithmetic number, because the mean of its divisors is an integer number (10606655665609).

Almost surely, 2^{21213311331217} is an apocalyptic number.

It is an amenable number.

21213311331217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213311331217 is an equidigital number, since it uses as much as digits as its factorization.

21213311331217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4536, while the sum is 31.

Adding to 21213311331217 its reverse (71213311331212), we get a palindrome (92426622662429).

The spelling of 21213311331217 in words is "twenty-one trillion, two hundred thirteen billion, three hundred eleven million, three hundred thirty-one thousand, two hundred seventeen".