105661 has 4 divisors (see below), whose sum is σ = 106492. Its totient is φ = 104832.

The previous prime is 105653. The next prime is 105667. The reversal of 105661 is 166501.

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.

It can be written as a sum of positive squares in 2 ways, for example, as 32761 + 72900 = 181^2 + 270^2 .

It is a cyclic number.

It is not a de Polignac number, because 105661 - 2³ = 105653 is a prime.

It is a super-2 number, since 2×105661² = 22328493842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (105667) 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 3 ways as a sum of consecutive naturals, for example, 180 + ... + 493.

It is an arithmetic number, because the mean of its divisors is an integer number (26623).

2¹⁰⁵⁶⁶¹ is an apocalyptic number.

It is an amenable number.

105661 is a deficient number, since it is larger than the sum of its proper divisors (831).

105661 is an equidigital number, since it uses as much as digits as its factorization.

105661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 105661 is about 325.0553798970. The cubic root of 105661 is about 47.2757294803.

It can be divided in two parts, 10 and 5661, that added together give a triangular number (5671 = T₁₀₆).

The spelling of 105661 in words is "one hundred five thousand, six hundred sixty-one".