161566560005581 has 4 divisors (see below), whose sum is σ = 161566589504992. Its totient is φ = 161566530506172.

The previous prime is 161566560005549. The next prime is 161566560005659. The reversal of 161566560005581 is 185500065665161.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161566560005581 - 2⁵ = 161566560005549 is a prime.

It is a super-2 number, since 2×161566560005581² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161566560000581) 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, 3848841 + ... + 18383326.

It is an arithmetic number, because the mean of its divisors is an integer number (40391647376248).

Almost surely, 2^{161566560005581} is an apocalyptic number.

It is an amenable number.

161566560005581 is a deficient number, since it is larger than the sum of its proper divisors (29499411).

161566560005581 is an equidigital number, since it uses as much as digits as its factorization.

161566560005581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29499410.

The product of its (nonzero) digits is 6480000, while the sum is 55.

The spelling of 161566560005581 in words is "one hundred sixty-one trillion, five hundred sixty-six billion, five hundred sixty million, five thousand, five hundred eighty-one".