188908021 has 2 divisors, whose sum is σ = 188908022. Its totient is φ = 188908020.

The previous prime is 188908019. The next prime is 188908043. The reversal of 188908021 is 120809881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 141491025 + 47416996 = 11895^2 + 6886^2 .

It is a cyclic number.

It is not a de Polignac number, because 188908021 - 2¹ = 188908019 is a prime.

Together with 188908019, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (188908061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94454010 + 94454011.

It is an arithmetic number, because the mean of its divisors is an integer number (94454011).

Almost surely, 2^188908021 is an apocalyptic number.

It is an amenable number.

188908021 is a deficient number, since it is larger than the sum of its proper divisors (1).

188908021 is an equidigital number, since it uses as much as digits as its factorization.

188908021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 188908021 is about 13744.3814338805. The cubic root of 188908021 is about 573.7862447536.

It can be divided in two parts, 188 and 908021, that added together give a square (908209 = 953²).

The spelling of 188908021 in words is "one hundred eighty-eight million, nine hundred eight thousand, twenty-one".