71665216523 has 4 divisors (see below), whose sum is σ = 71707548528. Its totient is φ = 71622884520.

The previous prime is 71665216501. The next prime is 71665216529. The reversal of 71665216523 is 32561256617.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32561256617 = 88223 ⋅369079.

It is a cyclic number.

It is not a de Polignac number, because 71665216523 - 2⁶ = 71665216459 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71665216529) 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 in 3 ways as a sum of consecutive naturals, for example, 21163463 + ... + 21166848.

It is an arithmetic number, because the mean of its divisors is an integer number (17926887132).

Almost surely, 2^71665216523 is an apocalyptic number.

71665216523 is a deficient number, since it is larger than the sum of its proper divisors (42332005).

71665216523 is a wasteful number, since it uses less digits than its factorization.

71665216523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42332004.

The product of its digits is 453600, while the sum is 44.

The spelling of 71665216523 in words is "seventy-one billion, six hundred sixty-five million, two hundred sixteen thousand, five hundred twenty-three".