2661665 has 4 divisors (see below), whose sum is σ = 3194004. Its totient is φ = 2129328.

The previous prime is 2661661. The next prime is 2661689. The reversal of 2661665 is 5661662.

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 1817104 + 844561 = 1348^2 + 919^2 .

It is a cyclic number.

It is not a de Polignac number, because 2661665 - 2² = 2661661 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2661661) 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, 266162 + ... + 266171.

It is an arithmetic number, because the mean of its divisors is an integer number (798501).

2^2661665 is an apocalyptic number.

It is an amenable number.

2661665 is a deficient number, since it is larger than the sum of its proper divisors (532339).

2661665 is an equidigital number, since it uses as much as digits as its factorization.

2661665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532338.

The product of its digits is 12960, while the sum is 32.

The square root of 2661665 is about 1631.4610016792. The cubic root of 2661665 is about 138.5855015593.

The spelling of 2661665 in words is "two million, six hundred sixty-one thousand, six hundred sixty-five".