161189723 has 4 divisors (see below), whose sum is σ = 165546240. Its totient is φ = 156833208.

The previous prime is 161189689. The next prime is 161189729. The reversal of 161189723 is 327981161.

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 161189723 - 2⁶ = 161189659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161189729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2178203 + ... + 2178276.

It is an arithmetic number, because the mean of its divisors is an integer number (41386560).

Almost surely, 2^161189723 is an apocalyptic number.

161189723 is a deficient number, since it is larger than the sum of its proper divisors (4356517).

161189723 is an equidigital number, since it uses as much as digits as its factorization.

161189723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4356516.

The product of its digits is 18144, while the sum is 38.

The square root of 161189723 is about 12696.0514728005. The cubic root of 161189723 is about 544.2257873203.

The spelling of 161189723 in words is "one hundred sixty-one million, one hundred eighty-nine thousand, seven hundred twenty-three".