2665861 has 16 divisors (see below), whose sum is σ = 3120768. Its totient is φ = 2252800.

The previous prime is 2665849. The next prime is 2665867. The reversal of 2665861 is 1685662.

It is not a de Polignac number, because 2665861 - 2¹¹ = 2663813 is a prime.

It is a Duffinian number.

2665861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2665867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10245 + ... + 10501.

It is an arithmetic number, because the mean of its divisors is an integer number (195048).

2^2665861 is an apocalyptic number.

2665861 is the 943-rd octagonal number.

It is an amenable number.

2665861 is a deficient number, since it is larger than the sum of its proper divisors (454907).

2665861 is a wasteful number, since it uses less digits than its factorization.

2665861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332.

The product of its digits is 17280, while the sum is 34.

The square root of 2665861 is about 1632.7464591908. The cubic root of 2665861 is about 138.6582880118.

The spelling of 2665861 in words is "two million, six hundred sixty-five thousand, eight hundred sixty-one".