2561865 has 32 divisors (see below), whose sum is σ = 4406400. Its totient is φ = 1267200.

The previous prime is 2561863. The next prime is 2561873. The reversal of 2561865 is 5681652.

2561865 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 2561865 - 2¹ = 2561863 is a prime.

It is a super-3 number, since 3×2561865³ = 50441730333764668875, which contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (2561863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 25315 + ... + 25415.

It is an arithmetic number, because the mean of its divisors is an integer number (137700).

2^2561865 is an apocalyptic number.

It is an amenable number.

2561865 is a deficient number, since it is larger than the sum of its proper divisors (1844535).

2561865 is a wasteful number, since it uses less digits than its factorization.

2561865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217.

The product of its digits is 14400, while the sum is 33.

The square root of 2561865 is about 1600.5827063916. The cubic root of 2561865 is about 136.8312875156.

The spelling of 2561865 in words is "two million, five hundred sixty-one thousand, eight hundred sixty-five".