71665656617 has 4 divisors (see below), whose sum is σ = 71667436740. Its totient is φ = 71663876496.

The previous prime is 71665656613. The next prime is 71665656659.

71665656617 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 66969158656 + 4696497961 = 258784^2 + 68531^2 .

It is a cyclic number.

It is not a de Polignac number, because 71665656617 - 2² = 71665656613 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71665656613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 828242 + ... + 910667.

It is an arithmetic number, because the mean of its divisors is an integer number (17916859185).

Almost surely, 2^71665656617 is an apocalyptic number.

It is an amenable number.

71665656617 is a deficient number, since it is larger than the sum of its proper divisors (1780123).

71665656617 is a wasteful number, since it uses less digits than its factorization.

71665656617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1780122.

The product of its digits is 9525600, while the sum is 56.

The spelling of 71665656617 in words is "seventy-one billion, six hundred sixty-five million, six hundred fifty-six thousand, six hundred seventeen".