71585865217 has 2 divisors, whose sum is σ = 71585865218. Its totient is φ = 71585865216.

The previous prime is 71585865179. The next prime is 71585865271. The reversal of 71585865217 is 71256858517.

Together with next prime (71585865271) 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., 71101689201 + 484176016 = 266649^2 + 22004^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71585865217 is a prime.

It is not a weakly prime, because it can be changed into another prime (71585865287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35792932608 + 35792932609.

It is an arithmetic number, because the mean of its divisors is an integer number (35792932609).

Almost surely, 2^71585865217 is an apocalyptic number.

It is an amenable number.

71585865217 is a deficient number, since it is larger than the sum of its proper divisors (1).

71585865217 is an equidigital number, since it uses as much as digits as its factorization.

71585865217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4704000, while the sum is 55.

The spelling of 71585865217 in words is "seventy-one billion, five hundred eighty-five million, eight hundred sixty-five thousand, two hundred seventeen".