161706021605 has 4 divisors (see below), whose sum is σ = 194047225932. Its totient is φ = 129364817280.

The previous prime is 161706021563. The next prime is 161706021611. The reversal of 161706021605 is 506120607161.

161706021605 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 506120607161 = 13 ⋅38932354397.

It can be written as a sum of positive squares in 2 ways, for example, as 107427273121 + 54278748484 = 327761^2 + 232978^2 .

It is not a de Polignac number, because 161706021605 - 2⁸ = 161706021349 is a prime.

It is a super-2 number, since 2×161706021605² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16170602156 + ... + 16170602165.

It is an arithmetic number, because the mean of its divisors is an integer number (48511806483).

Almost surely, 2^161706021605 is an apocalyptic number.

It is an amenable number.

161706021605 is a deficient number, since it is larger than the sum of its proper divisors (32341204327).

161706021605 is an equidigital number, since it uses as much as digits as its factorization.

161706021605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32341204326.

The product of its (nonzero) digits is 15120, while the sum is 35.

Adding to 161706021605 its reverse (506120607161), we get a palindrome (667826628766).

The spelling of 161706021605 in words is "one hundred sixty-one billion, seven hundred six million, twenty-one thousand, six hundred five".