188721 has 12 divisors (see below), whose sum is σ = 293748. Its totient is φ = 116064.

The previous prime is 188719. The next prime is 188729. The reversal of 188721 is 127881.

It can be written as a sum of positive squares in 2 ways, for example, as 69696 + 119025 = 264^2 + 345^2 .

It is not a de Polignac number, because 188721 - 2¹ = 188719 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 188721.

It is not an unprimeable number, because it can be changed into a prime (188729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 690 + ... + 923.

It is an arithmetic number, because the mean of its divisors is an integer number (24479).

2¹⁸⁸⁷²¹ is an apocalyptic number.

It is an amenable number.

188721 is a deficient number, since it is larger than the sum of its proper divisors (105027).

188721 is a wasteful number, since it uses less digits than its factorization.

188721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1632 (or 1629 counting only the distinct ones).

The product of its digits is 896, while the sum is 27.

The square root of 188721 is about 434.4203033929. The cubic root of 188721 is about 57.3596830687.

It can be divided in two parts, 188 and 721, that added together give a palindrome (909).

The spelling of 188721 in words is "one hundred eighty-eight thousand, seven hundred twenty-one".