2159665 has 4 divisors (see below), whose sum is σ = 2591604. Its totient is φ = 1727728.

The previous prime is 2159639. The next prime is 2159669. The reversal of 2159665 is 5669512.

It is a happy number.

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 419904 + 1739761 = 648^2 + 1319^2 .

It is a cyclic number.

It is not a de Polignac number, because 2159665 - 2⁷ = 2159537 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2159665.

It is not an unprimeable number, because it can be changed into a prime (2159669) 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, 215962 + ... + 215971.

It is an arithmetic number, because the mean of its divisors is an integer number (647901).

2^2159665 is an apocalyptic number.

It is an amenable number.

2159665 is a deficient number, since it is larger than the sum of its proper divisors (431939).

2159665 is an equidigital number, since it uses as much as digits as its factorization.

2159665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431938.

The product of its digits is 16200, while the sum is 34.

The square root of 2159665 is about 1469.5798719362. The cubic root of 2159665 is about 129.2593983192.

The spelling of 2159665 in words is "two million, one hundred fifty-nine thousand, six hundred sixty-five".