188561 has 4 divisors (see below), whose sum is σ = 189732. Its totient is φ = 187392.

The previous prime is 188533. The next prime is 188563. The reversal of 188561 is 165881.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 165881 = 31 ⋅5351.

It can be written as a sum of positive squares in 2 ways, for example, as 118336 + 70225 = 344^2 + 265^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-188561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (188563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 296 + ... + 681.

It is an arithmetic number, because the mean of its divisors is an integer number (47433).

2¹⁸⁸⁵⁶¹ is an apocalyptic number.

It is an amenable number.

188561 is a deficient number, since it is larger than the sum of its proper divisors (1171).

188561 is an equidigital number, since it uses as much as digits as its factorization.

188561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1170.

The product of its digits is 1920, while the sum is 29.

The square root of 188561 is about 434.2361108890. The cubic root of 188561 is about 57.3434684024.

The spelling of 188561 in words is "one hundred eighty-eight thousand, five hundred sixty-one".