161605501111111 has 4 divisors (see below), whose sum is σ = 161613682445152. Its totient is φ = 161597319777072.

The previous prime is 161605501111099. The next prime is 161605501111133. The reversal of 161605501111111 is 111111105506161.

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

It is a cyclic number.

It is not a de Polignac number, because 161605501111111 - 2³⁵ = 161571141372743 is a prime.

It is a super-2 number, since 2×161605501111111² (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 (161605501111181) 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, 4090637391 + ... + 4090676896.

It is an arithmetic number, because the mean of its divisors is an integer number (40403420611288).

Almost surely, 2^{161605501111111} is an apocalyptic number.

161605501111111 is a deficient number, since it is larger than the sum of its proper divisors (8181334041).

161605501111111 is an equidigital number, since it uses as much as digits as its factorization.

161605501111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8181334040.

The product of its (nonzero) digits is 900, while the sum is 31.

Adding to 161605501111111 its reverse (111111105506161), we get a palindrome (272716606617272).

The spelling of 161605501111111 in words is "one hundred sixty-one trillion, six hundred five billion, five hundred one million, one hundred eleven thousand, one hundred eleven".