188821 has 4 divisors (see below), whose sum is σ = 194944. Its totient is φ = 182700.

The previous prime is 188801. The next prime is 188827. The reversal of 188821 is 128881.

188821 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, and also an emirpimes, since its reverse is a distinct semiprime: 128881 = 359².

It is a cyclic number.

It is not a de Polignac number, because 188821 - 2⁷ = 188693 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 188821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (188827) 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, 3015 + ... + 3076.

It is an arithmetic number, because the mean of its divisors is an integer number (48736).

2¹⁸⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

188821 is a deficient number, since it is larger than the sum of its proper divisors (6123).

188821 is an equidigital number, since it uses as much as digits as its factorization.

188821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6122.

The product of its digits is 1024, while the sum is 28.

The square root of 188821 is about 434.5353840598. The cubic root of 188821 is about 57.3698125817.

The spelling of 188821 in words is "one hundred eighty-eight thousand, eight hundred twenty-one".