2161709 has 4 divisors (see below), whose sum is σ = 2358240. Its totient is φ = 1965180.

The previous prime is 2161699. The next prime is 2161729. The reversal of 2161709 is 9071612.

2161709 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a de Polignac number, because none of the positive numbers 2^k-2161709 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161729) 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, 98249 + ... + 98270.

It is an arithmetic number, because the mean of its divisors is an integer number (589560).

2^2161709 is an apocalyptic number.

It is an amenable number.

2161709 is a deficient number, since it is larger than the sum of its proper divisors (196531).

2161709 is a wasteful number, since it uses less digits than its factorization.

2161709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196530.

The product of its (nonzero) digits is 756, while the sum is 26.

The square root of 2161709 is about 1470.2751443182. The cubic root of 2161709 is about 129.3001643488.

Subtracting 2161709 from its reverse (9071612), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 2161709 in words is "two million, one hundred sixty-one thousand, seven hundred nine".