188511989 has 2 divisors, whose sum is σ = 188511990. Its totient is φ = 188511988.

The previous prime is 188511949. The next prime is 188512033. The reversal of 188511989 is 989115881.

188511989 = 7926² + 7927² + 7928².

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 142611364 + 45900625 = 11942^2 + 6775^2 .

It is a cyclic number.

It is not a de Polignac number, because 188511989 - 2²⁰ = 187463413 is a prime.

It is a super-2 number, since 2×188511989² = 71073539993472242, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen 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 (188511949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94255994 + 94255995.

It is an arithmetic number, because the mean of its divisors is an integer number (94255995).

Almost surely, 2^188511989 is an apocalyptic number.

It is an amenable number.

188511989 is a deficient number, since it is larger than the sum of its proper divisors (1).

188511989 is an equidigital number, since it uses as much as digits as its factorization.

188511989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 207360, while the sum is 50.

The square root of 188511989 is about 13729.9668244319. The cubic root of 188511989 is about 573.3849971096.

The spelling of 188511989 in words is "one hundred eighty-eight million, five hundred eleven thousand, nine hundred eighty-nine".