2165391 has 6 divisors (see below), whose sum is σ = 3127800. Its totient is φ = 1443588.

The previous prime is 2165357. The next prime is 2165393. The reversal of 2165391 is 1935612.

2165391 is a `hidden beast` number, since 2 + 1 + 653 + 9 + 1 = 666.

It is not a de Polignac number, because 2165391 - 2⁶ = 2165327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2165393) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 120291 + ... + 120308.

It is an arithmetic number, because the mean of its divisors is an integer number (521300).

2^2165391 is an apocalyptic number.

2165391 is a deficient number, since it is larger than the sum of its proper divisors (962409).

2165391 is a wasteful number, since it uses less digits than its factorization.

2165391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240605 (or 240602 counting only the distinct ones).

The product of its digits is 1620, while the sum is 27.

The square root of 2165391 is about 1471.5267581665. The cubic root of 2165391 is about 129.3735342549.

It can be divided in two parts, 2165 and 391, that added together give a triangular number (2556 = T₇₁).

The spelling of 2165391 in words is "two million, one hundred sixty-five thousand, three hundred ninety-one".