81717271697 has 2 divisors, whose sum is σ = 81717271698. Its totient is φ = 81717271696.

The previous prime is 81717271679. The next prime is 81717271721. The reversal of 81717271697 is 79617271718.

Together with previous prime (81717271679) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 58545125521 + 23172146176 = 241961^2 + 152224^2 .

It is a cyclic number.

It is not a de Polignac number, because 81717271697 - 2²² = 81713077393 is a prime.

It is a super-3 number, since 3×81717271697³ (a number of 34 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (81717271997) 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, 40858635848 + 40858635849.

It is an arithmetic number, because the mean of its divisors is an integer number (40858635849).

Almost surely, 2^81717271697 is an apocalyptic number.

It is an amenable number.

81717271697 is a deficient number, since it is larger than the sum of its proper divisors (1).

81717271697 is an equidigital number, since it uses as much as digits as its factorization.

81717271697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2074464, while the sum is 56.

The spelling of 81717271697 in words is "eighty-one billion, seven hundred seventeen million, two hundred seventy-one thousand, six hundred ninety-seven".