161909845 has 8 divisors (see below), whose sum is σ = 194398776. Its totient is φ = 129456576.

The previous prime is 161909801. The next prime is 161909863. The reversal of 161909845 is 548909161.

It can be written as a sum of positive squares in 4 ways, for example, as 21511044 + 140398801 = 4638^2 + 11849^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161909845 - 2¹³ = 161901653 is a prime.

It is a super-3 number, since 3×161909845³ (a number of 26 digits) contains 333 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 (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2379 + ... + 18151.

It is an arithmetic number, because the mean of its divisors is an integer number (24299847).

Almost surely, 2^161909845 is an apocalyptic number.

It is an amenable number.

161909845 is a deficient number, since it is larger than the sum of its proper divisors (32488931).

161909845 is a wasteful number, since it uses less digits than its factorization.

161909845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17831.

The product of its (nonzero) digits is 77760, while the sum is 43.

The square root of 161909845 is about 12724.3799456005. The cubic root of 161909845 is about 545.0350340804.

The spelling of 161909845 in words is "one hundred sixty-one million, nine hundred nine thousand, eight hundred forty-five".