181720 has 64 divisors (see below), whose sum is σ = 518400. Its totient is φ = 55680.

The previous prime is 181717. The next prime is 181721. The reversal of 181720 is 27181.

181720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3051 + ... + 3109.

It is an arithmetic number, because the mean of its divisors is an integer number (8100).

2¹⁸¹⁷²⁰ is an apocalyptic number.

181720 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 181720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (259200).

181720 is an abundant number, since it is smaller than the sum of its proper divisors (336680).

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

181720 is a wasteful number, since it uses less digits than its factorization.

181720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 19.

The square root of 181720 is about 426.2862887779. The cubic root of 181720 is about 56.6414343642.

The spelling of 181720 in words is "one hundred eighty-one thousand, seven hundred twenty".