161605566661601 has 32 divisors (see below), whose sum is σ = 170500206624768. Its totient is φ = 152874817603200.

The previous prime is 161605566661549. The next prime is 161605566661619. The reversal of 161605566661601 is 106166665506161.

161605566661601 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161605566661601 is a prime.

It is a super-2 number, since 2×161605566661601² (a number of 29 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (56) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161605566661621) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2014816040 + ... + 2014896246.

It is an arithmetic number, because the mean of its divisors is an integer number (5328131457024).

Almost surely, 2^{161605566661601} is an apocalyptic number.

It is an amenable number.

161605566661601 is a deficient number, since it is larger than the sum of its proper divisors (8894639963167).

161605566661601 is a wasteful number, since it uses less digits than its factorization.

161605566661601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82541.

The product of its (nonzero) digits is 6998400, while the sum is 56.

The spelling of 161605566661601 in words is "one hundred sixty-one trillion, six hundred five billion, five hundred sixty-six million, six hundred sixty-one thousand, six hundred one".