21353434217 has 2 divisors, whose sum is σ = 21353434218. Its totient is φ = 21353434216.

The previous prime is 21353434177. The next prime is 21353434237. The reversal of 21353434217 is 71243435312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18908725081 + 2444709136 = 137509^2 + 49444^2 .

It is a cyclic number.

It is not a de Polignac number, because 21353434217 - 2¹⁰ = 21353433193 is a prime.

It is not a weakly prime, because it can be changed into another prime (21353434237) 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, 10676717108 + 10676717109.

It is an arithmetic number, because the mean of its divisors is an integer number (10676717109).

Almost surely, 2^21353434217 is an apocalyptic number.

It is an amenable number.

21353434217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21353434217 is an equidigital number, since it uses as much as digits as its factorization.

21353434217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60480, while the sum is 35.

Adding to 21353434217 its reverse (71243435312), we get a palindrome (92596869529).

The spelling of 21353434217 in words is "twenty-one billion, three hundred fifty-three million, four hundred thirty-four thousand, two hundred seventeen".