188199989 has 2 divisors, whose sum is σ = 188199990. Its totient is φ = 188199988.

The previous prime is 188199943. The next prime is 188200043. The reversal of 188199989 is 989991881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 133217764 + 54982225 = 11542^2 + 7415^2 .

It is a cyclic number.

It is not a de Polignac number, because 188199989 - 2⁸ = 188199733 is a prime.

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 (188193989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94099994 + 94099995.

It is an arithmetic number, because the mean of its divisors is an integer number (94099995).

Almost surely, 2^188199989 is an apocalyptic number.

It is an amenable number.

188199989 is a deficient number, since it is larger than the sum of its proper divisors (1).

188199989 is an equidigital number, since it uses as much as digits as its factorization.

188199989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3359232, while the sum is 62.

The square root of 188199989 is about 13718.6001107985. The cubic root of 188199989 is about 573.0684922091.

The spelling of 188199989 in words is "one hundred eighty-eight million, one hundred ninety-nine thousand, nine hundred eighty-nine".