161605565050565 has 4 divisors (see below), whose sum is σ = 193926678060684. Its totient is φ = 129284452040448.

The previous prime is 161605565050459. The next prime is 161605565050591. The reversal of 161605565050565 is 565050565506161.

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 31834804510756 + 129770760539809 = 5642234^2 + 11391697^2 .

It is a cyclic number.

It is not a de Polignac number, because 161605565050565 - 2³⁴ = 161588385181381 is a prime.

It is a super-2 number, since 2×161605565050565² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 161605565050565.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16160556505052 + ... + 16160556505061.

It is an arithmetic number, because the mean of its divisors is an integer number (48481669515171).

Almost surely, 2^{161605565050565} is an apocalyptic number.

It is an amenable number.

161605565050565 is a deficient number, since it is larger than the sum of its proper divisors (32321113010119).

161605565050565 is an equidigital number, since it uses as much as digits as its factorization.

161605565050565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32321113010118.

The product of its (nonzero) digits is 20250000, while the sum is 56.

The spelling of 161605565050565 in words is "one hundred sixty-one trillion, six hundred five billion, five hundred sixty-five million, fifty thousand, five hundred sixty-five".