188866861 has 2 divisors, whose sum is σ = 188866862. Its totient is φ = 188866860.

The previous prime is 188866837. The next prime is 188866883. The reversal of 188866861 is 168668881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 181413961 + 7452900 = 13469^2 + 2730^2 .

It is an emirp because it is prime and its reverse (168668881) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 198998881 and 188899891.

It is a cyclic number.

It is not a de Polignac number, because 188866861 - 2²³ = 180478253 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 188866799 and 188866808.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (188866831) 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, 94433430 + 94433431.

It is an arithmetic number, because the mean of its divisors is an integer number (94433431).

Almost surely, 2^188866861 is an apocalyptic number.

It is an amenable number.

188866861 is a deficient number, since it is larger than the sum of its proper divisors (1).

188866861 is an equidigital number, since it uses as much as digits as its factorization.

188866861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 884736, while the sum is 52.

The square root of 188866861 is about 13742.8840131902. The cubic root of 188866861 is about 573.7445688149.

The spelling of 188866861 in words is "one hundred eighty-eight million, eight hundred sixty-six thousand, eight hundred sixty-one".