188899891 has 2 divisors, whose sum is σ = 188899892. Its totient is φ = 188899890.

The previous prime is 188899889. The next prime is 188899901. The reversal of 188899891 is 198998881.

It is a weak prime.

It is an emirp because it is prime and its reverse (198998881) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 168668881 and 188866861.

It is a cyclic number.

It is not a de Polignac number, because 188899891 - 2¹ = 188899889 is a prime.

Together with 188899889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (188899811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94449945 + 94449946.

It is an arithmetic number, because the mean of its divisors is an integer number (94449946).

Almost surely, 2^188899891 is an apocalyptic number.

188899891 is a deficient number, since it is larger than the sum of its proper divisors (1).

188899891 is an equidigital number, since it uses as much as digits as its factorization.

188899891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2985984, while the sum is 61.

The square root of 188899891 is about 13744.0856734815. The cubic root of 188899891 is about 573.7780133243.

The spelling of 188899891 in words is "one hundred eighty-eight million, eight hundred ninety-nine thousand, eight hundred ninety-one".