185661 has 18 divisors (see below), whose sum is σ = 312702. Its totient is φ = 105840.

The previous prime is 185651. The next prime is 185677. The reversal of 185661 is 166581.

It can be written as a sum of positive squares in only one way, i.e., 99225 + 86436 = 315^2 + 294^2 .

It is not a de Polignac number, because 185661 - 2⁷ = 185533 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (185621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 231 + ... + 651.

2¹⁸⁵⁶⁶¹ is an apocalyptic number.

It is an amenable number.

185661 is a deficient number, since it is larger than the sum of its proper divisors (127041).

185661 is a wasteful number, since it uses less digits than its factorization.

185661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 441 (or 431 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 185661 is about 430.8839751023. The cubic root of 185661 is about 57.0479743845.

The spelling of 185661 in words is "one hundred eighty-five thousand, six hundred sixty-one".