187921 has 2 divisors, whose sum is σ = 187922. Its totient is φ = 187920.

The previous prime is 187909. The next prime is 187927. The reversal of 187921 is 129781.

187921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 130321 + 57600 = 361^2 + 240^2 .

It is a cyclic number.

It is not a de Polignac number, because 187921 - 2⁷ = 187793 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 187921.

It is not a weakly prime, because it can be changed into another prime (187927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 93960 + 93961.

It is an arithmetic number, because the mean of its divisors is an integer number (93961).

2¹⁸⁷⁹²¹ is an apocalyptic number.

It is an amenable number.

187921 is a deficient number, since it is larger than the sum of its proper divisors (1).

187921 is an equidigital number, since it uses as much as digits as its factorization.

187921 is an odious number, because the sum of its binary digits is odd.

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

The square root of 187921 is about 433.4985582444. The cubic root of 187921 is about 57.2785178567.

The spelling of 187921 in words is "one hundred eighty-seven thousand, nine hundred twenty-one".