217517210681 has 2 divisors, whose sum is σ = 217517210682. Its totient is φ = 217517210680.

The previous prime is 217517210671. The next prime is 217517210699. The reversal of 217517210681 is 186012715712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 193217389225 + 24299821456 = 439565^2 + 155884^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217517210681 is a prime.

It is a super-2 number, since 2×217517210681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (217517210671) 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, 108758605340 + 108758605341.

It is an arithmetic number, because the mean of its divisors is an integer number (108758605341).

Almost surely, 2^217517210681 is an apocalyptic number.

It is an amenable number.

217517210681 is a deficient number, since it is larger than the sum of its proper divisors (1).

217517210681 is an equidigital number, since it uses as much as digits as its factorization.

217517210681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 47040, while the sum is 41.

The spelling of 217517210681 in words is "two hundred seventeen billion, five hundred seventeen million, two hundred ten thousand, six hundred eighty-one".