161661723 has 4 divisors (see below), whose sum is σ = 215548968. Its totient is φ = 107774480.

The previous prime is 161661707. The next prime is 161661739. The reversal of 161661723 is 327166161.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (161661707) and next prime (161661739).

It is a cyclic number.

It is not a de Polignac number, because 161661723 - 2⁴ = 161661707 is a prime.

It is a super-2 number, since 2×161661723² = 52269025366657458, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161661323) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 26943618 + ... + 26943623.

It is an arithmetic number, because the mean of its divisors is an integer number (53887242).

Almost surely, 2^161661723 is an apocalyptic number.

161661723 is a deficient number, since it is larger than the sum of its proper divisors (53887245).

161661723 is an equidigital number, since it uses as much as digits as its factorization.

161661723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53887244.

The product of its digits is 9072, while the sum is 33.

The square root of 161661723 is about 12714.6263413441. The cubic root of 161661723 is about 544.7564751023.

The spelling of 161661723 in words is "one hundred sixty-one million, six hundred sixty-one thousand, seven hundred twenty-three".