2109661 has 4 divisors (see below), whose sum is σ = 2115324. Its totient is φ = 2104000.

The previous prime is 2109647. The next prime is 2109671. The reversal of 2109661 is 1669012.

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 1907161 + 202500 = 1381^2 + 450^2 .

It is a cyclic number.

It is not a de Polignac number, because 2109661 - 2⁷ = 2109533 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 (2109641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2230 + ... + 3031.

It is an arithmetic number, because the mean of its divisors is an integer number (528831).

2^2109661 is an apocalyptic number.

It is an amenable number.

2109661 is a deficient number, since it is larger than the sum of its proper divisors (5663).

2109661 is an equidigital number, since it uses as much as digits as its factorization.

2109661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5662.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 2109661 is about 1452.4672113339. The cubic root of 2109661 is about 128.2539919239.

The spelling of 2109661 in words is "two million, one hundred nine thousand, six hundred sixty-one".