2561405 has 16 divisors (see below), whose sum is σ = 3832704. Its totient is φ = 1596480.

The previous prime is 2561401. The next prime is 2561411. The reversal of 2561405 is 5041652.

It is not a de Polignac number, because 2561405 - 2² = 2561401 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2942 + ... + 3711.

It is an arithmetic number, because the mean of its divisors is an integer number (239544).

2^2561405 is an apocalyptic number.

It is an amenable number.

2561405 is a deficient number, since it is larger than the sum of its proper divisors (1271299).

2561405 is a wasteful number, since it uses less digits than its factorization.

2561405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6676.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 2561405 is about 1600.4390022741. The cubic root of 2561405 is about 136.8230973676.

It can be divided in two parts, 256 and 1405, that added together give a palindrome (1661).

The spelling of 2561405 in words is "two million, five hundred sixty-one thousand, four hundred five".