2165729 has 4 divisors (see below), whose sum is σ = 2169876. Its totient is φ = 2161584.

The previous prime is 2165711. The next prime is 2165741. The reversal of 2165729 is 9275612.

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 677329 + 1488400 = 823^2 + 1220^2 .

It is a cyclic number.

It is not a de Polignac number, because 2165729 - 2¹² = 2161633 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2165695 and 2165704.

It is not an unprimeable number, because it can be changed into a prime (2165029) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1154 + ... + 2379.

It is an arithmetic number, because the mean of its divisors is an integer number (542469).

2^2165729 is an apocalyptic number.

It is an amenable number.

2165729 is a deficient number, since it is larger than the sum of its proper divisors (4147).

2165729 is an equidigital number, since it uses as much as digits as its factorization.

2165729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4146.

The product of its digits is 7560, while the sum is 32.

The square root of 2165729 is about 1471.6416003905. The cubic root of 2165729 is about 129.3802652917.

The spelling of 2165729 in words is "two million, one hundred sixty-five thousand, seven hundred twenty-nine".