161005165665665 has 4 divisors (see below), whose sum is σ = 193206198798804. Its totient is φ = 128804132532528.

The previous prime is 161005165665649. The next prime is 161005165665671. The reversal of 161005165665665 is 566566561500161.

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 118892178405361 + 42112987260304 = 10903769^2 + 6489452^2 .

It is a cyclic number.

It is not a de Polignac number, because 161005165665665 - 2⁴ = 161005165665649 is a prime.

It is a Duffinian number.

It is a Curzon 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, 16100516566562 + ... + 16100516566571.

It is an arithmetic number, because the mean of its divisors is an integer number (48301549699701).

Almost surely, 2^{161005165665665} is an apocalyptic number.

It is an amenable number.

161005165665665 is a deficient number, since it is larger than the sum of its proper divisors (32201033133139).

161005165665665 is an equidigital number, since it uses as much as digits as its factorization.

161005165665665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32201033133138.

The product of its (nonzero) digits is 29160000, while the sum is 59.

The spelling of 161005165665665 in words is "one hundred sixty-one trillion, five billion, one hundred sixty-five million, six hundred sixty-five thousand, six hundred sixty-five".