2165761 has 4 divisors (see below), whose sum is σ = 2332372. Its totient is φ = 1999152.

The previous prime is 2165747. The next prime is 2165771. The reversal of 2165761 is 1675612.

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 1050625 + 1115136 = 1025^2 + 1056^2 .

It is a cyclic number.

It is not a de Polignac number, because 2165761 - 2⁹ = 2165249 is a prime.

It is a Duffinian number.

2165761 is a lucky number.

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

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 83286 + ... + 83311.

It is an arithmetic number, because the mean of its divisors is an integer number (583093).

2^2165761 is an apocalyptic number.

It is an amenable number.

2165761 is a deficient number, since it is larger than the sum of its proper divisors (166611).

2165761 is a wasteful number, since it uses less digits than its factorization.

2165761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166610.

The product of its digits is 2520, while the sum is 28.

The square root of 2165761 is about 1471.6524725627. The cubic root of 2165761 is about 129.3809025133.

It can be divided in two parts, 2165 and 761, that added together give a triangular number (2926 = T₇₆).

The spelling of 2165761 in words is "two million, one hundred sixty-five thousand, seven hundred sixty-one".