2161909 has 4 divisors (see below), whose sum is σ = 2231680. Its totient is φ = 2092140.

The previous prime is 2161903. The next prime is 2161919. The reversal of 2161909 is 9091612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2161909 - 2⁷ = 2161781 is a prime.

It is a Duffinian number.

2161909 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34839 + ... + 34900.

It is an arithmetic number, because the mean of its divisors is an integer number (557920).

2^2161909 is an apocalyptic number.

It is an amenable number.

2161909 is a deficient number, since it is larger than the sum of its proper divisors (69771).

2161909 is an equidigital number, since it uses as much as digits as its factorization.

2161909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69770.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 2161909 is about 1470.3431572256. The cubic root of 2161909 is about 129.3041518166.

The spelling of 2161909 in words is "two million, one hundred sixty-one thousand, nine hundred nine".