188561881 has 2 divisors, whose sum is σ = 188561882. Its totient is φ = 188561880.

The previous prime is 188561839. The next prime is 188561903. The reversal of 188561881 is 188165881.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 119006281 + 69555600 = 10909^2 + 8340^2 .

It is an emirp because it is prime and its reverse (188165881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 188561881 - 2⁹ = 188561369 is a prime.

It is a super-2 number, since 2×188561881² = 71111165932516322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (188561801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94280940 + 94280941.

It is an arithmetic number, because the mean of its divisors is an integer number (94280941).

Almost surely, 2^188561881 is an apocalyptic number.

It is an amenable number.

188561881 is a deficient number, since it is larger than the sum of its proper divisors (1).

188561881 is an equidigital number, since it uses as much as digits as its factorization.

188561881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 122880, while the sum is 46.

The square root of 188561881 is about 13731.7836059268. The cubic root of 188561881 is about 573.4355770949.

The spelling of 188561881 in words is "one hundred eighty-eight million, five hundred sixty-one thousand, eight hundred eighty-one".