188905 has 4 divisors (see below), whose sum is σ = 226692. Its totient is φ = 151120.

The previous prime is 188891. The next prime is 188911. The reversal of 188905 is 509881.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 114921 + 73984 = 339^2 + 272^2 .

It is a de Polignac number, because none of the positive numbers 2^k-188905 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18886 + ... + 18895.

It is an arithmetic number, because the mean of its divisors is an integer number (56673).

2¹⁸⁸⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

188905 is a deficient number, since it is larger than the sum of its proper divisors (37787).

188905 is an equidigital number, since it uses as much as digits as its factorization.

188905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37786.

The product of its (nonzero) digits is 2880, while the sum is 31.

The square root of 188905 is about 434.6320282722. The cubic root of 188905 is about 57.3783186091.

The spelling of 188905 in words is "one hundred eighty-eight thousand, nine hundred five".