161193720 has 144 divisors (see below), whose sum is σ = 518876280. Its totient is φ = 40055040.

The previous prime is 161193679. The next prime is 161193737. The reversal of 161193720 is 27391161.

161193720 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 2642490 + ... + 2642550.

Almost surely, 2^161193720 is an apocalyptic number.

161193720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161193720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (259438140).

161193720 is an abundant number, since it is smaller than the sum of its proper divisors (357682560).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161193720 is a wasteful number, since it uses less digits than its factorization.

161193720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 2268, while the sum is 30.

The square root of 161193720 is about 12696.2088829698. The cubic root of 161193720 is about 544.2302856478.

Multiplying 161193720 by its sum of digits (30), we get a square (4835811600 = 69540²).

161193720 divided by its sum of digits (30) gives a square (5373124 = 2318²).

The spelling of 161193720 in words is "one hundred sixty-one million, one hundred ninety-three thousand, seven hundred twenty".