189721 has 4 divisors (see below), whose sum is σ = 216832. Its totient is φ = 162612.

The previous prime is 189713. The next prime is 189733. The reversal of 189721 is 127981.

189721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 189721 - 2³ = 189713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 189721.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13545 + ... + 13558.

It is an arithmetic number, because the mean of its divisors is an integer number (54208).

2¹⁸⁹⁷²¹ is an apocalyptic number.

It is an amenable number.

189721 is a deficient number, since it is larger than the sum of its proper divisors (27111).

189721 is an equidigital number, since it uses as much as digits as its factorization.

189721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27110.

The product of its digits is 1008, while the sum is 28.

The square root of 189721 is about 435.5697418325. The cubic root of 189721 is about 57.4608176664.

The spelling of 189721 in words is "one hundred eighty-nine thousand, seven hundred twenty-one".