188921 has 4 divisors (see below), whose sum is σ = 200052. Its totient is φ = 177792.

The previous prime is 188911. The next prime is 188927. The reversal of 188921 is 129881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129881 = 23 ⋅5647.

It can be written as a sum of positive squares in 2 ways, for example, as 55696 + 133225 = 236^2 + 365^2 .

It is a cyclic number.

It is not a de Polignac number, because 188921 - 2⁶ = 188857 is a prime.

It is a super-2 number, since 2×188921² = 71382288482, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (188927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5540 + ... + 5573.

It is an arithmetic number, because the mean of its divisors is an integer number (50013).

2¹⁸⁸⁹²¹ is an apocalyptic number.

It is an amenable number.

188921 is a deficient number, since it is larger than the sum of its proper divisors (11131).

188921 is a wasteful number, since it uses less digits than its factorization.

188921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11130.

The product of its digits is 1152, while the sum is 29.

The square root of 188921 is about 434.6504342572. The cubic root of 188921 is about 57.3799385189.

The spelling of 188921 in words is "one hundred eighty-eight thousand, nine hundred twenty-one".