21213333217 has 2 divisors, whose sum is σ = 21213333218. Its totient is φ = 21213333216.

The previous prime is 21213333203. The next prime is 21213333359. The reversal of 21213333217 is 71233331212.

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., 14397840081 + 6815493136 = 119991^2 + 82556^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213333217 is a prime.

It is not a weakly prime, because it can be changed into another prime (21213333517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606666608 + 10606666609.

It is an arithmetic number, because the mean of its divisors is an integer number (10606666609).

Almost surely, 2^21213333217 is an apocalyptic number.

It is an amenable number.

21213333217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213333217 is an equidigital number, since it uses as much as digits as its factorization.

21213333217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4536, while the sum is 28.

Adding to 21213333217 its reverse (71233331212), we get a palindrome (92446664429).

It can be divided in two parts, 212133 and 33217, that added together give a triangular number (245350 = T₇₀₀).

The spelling of 21213333217 in words is "twenty-one billion, two hundred thirteen million, three hundred thirty-three thousand, two hundred seventeen".