2165709 has 16 divisors (see below), whose sum is σ = 3554432. Its totient is φ = 1142208.

The previous prime is 2165707. The next prime is 2165711. The reversal of 2165709 is 9075612.

It is an interprime number because it is at equal distance from previous prime (2165707) and next prime (2165711).

It is not a de Polignac number, because 2165709 - 2¹ = 2165707 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2165701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3694 + ... + 4239.

It is an arithmetic number, because the mean of its divisors is an integer number (222152).

2^2165709 is an apocalyptic number.

It is an amenable number.

2165709 is a deficient number, since it is larger than the sum of its proper divisors (1388723).

2165709 is a wasteful number, since it uses less digits than its factorization.

2165709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7956.

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 2165709 is about 1471.6348052421. The cubic root of 2165709 is about 129.3798670250.

Subtracting 2165709 from its reverse (9075612), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 2165709 in words is "two million, one hundred sixty-five thousand, seven hundred nine".