2106661 has 4 divisors (see below), whose sum is σ = 2109772. Its totient is φ = 2103552.

The previous prime is 2106653. The next prime is 2106673. The reversal of 2106661 is 1666012.

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 690561 + 1416100 = 831^2 + 1190^2 .

It is a cyclic number.

It is not a de Polignac number, because 2106661 - 2³ = 2106653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2106631) 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, 60 + ... + 2053.

It is an arithmetic number, because the mean of its divisors is an integer number (527443).

2^2106661 is an apocalyptic number.

It is an amenable number.

2106661 is a deficient number, since it is larger than the sum of its proper divisors (3111).

2106661 is an equidigital number, since it uses as much as digits as its factorization.

2106661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3110.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 2106661 is about 1451.4341183809. The cubic root of 2106661 is about 128.1931694346.

The spelling of 2106661 in words is "two million, one hundred six thousand, six hundred sixty-one".