71656220161 has 4 divisors (see below), whose sum is σ = 72637812292. Its totient is φ = 70674628032.

The previous prime is 71656220149. The next prime is 71656220177. The reversal of 71656220161 is 16102265617.

It is a happy number.

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 45978080625 + 25678139536 = 214425^2 + 160244^2 .

It is a cyclic number.

It is not a de Polignac number, because 71656220161 - 2²⁵ = 71622665729 is a prime.

It is a super-2 number, since 2×71656220161² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 71656220161.

It is not an unprimeable number, because it can be changed into a prime (71656220561) 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, 490795956 + ... + 490796101.

It is an arithmetic number, because the mean of its divisors is an integer number (18159453073).

Almost surely, 2^71656220161 is an apocalyptic number.

It is an amenable number.

71656220161 is a deficient number, since it is larger than the sum of its proper divisors (981592131).

71656220161 is an equidigital number, since it uses as much as digits as its factorization.

71656220161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 981592130.

The product of its (nonzero) digits is 30240, while the sum is 37.

Adding to 71656220161 its reverse (16102265617), we get a palindrome (87758485778).

The spelling of 71656220161 in words is "seventy-one billion, six hundred fifty-six million, two hundred twenty thousand, one hundred sixty-one".