188985509 has 2 divisors, whose sum is σ = 188985510. Its totient is φ = 188985508.

The previous prime is 188985499. The next prime is 188985553. The reversal of 188985509 is 905589881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 138532900 + 50452609 = 11770^2 + 7103^2 .

It is a cyclic number.

It is not a de Polignac number, because 188985509 - 2⁸ = 188985253 is a prime.

It is a super-2 number, since 2×188985509² = 71431045223978162, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (188985809) 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, 94492754 + 94492755.

It is an arithmetic number, because the mean of its divisors is an integer number (94492755).

Almost surely, 2^188985509 is an apocalyptic number.

It is an amenable number.

188985509 is a deficient number, since it is larger than the sum of its proper divisors (1).

188985509 is an equidigital number, since it uses as much as digits as its factorization.

188985509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1036800, while the sum is 53.

The square root of 188985509 is about 13747.2000421904. The cubic root of 188985509 is about 573.8646876390.

The spelling of 188985509 in words is "one hundred eighty-eight million, nine hundred eighty-five thousand, five hundred nine".