2561866 has 16 divisors (see below), whose sum is σ = 4104000. Its totient is φ = 1195200.

The previous prime is 2561863. The next prime is 2561873. The reversal of 2561866 is 6681652.

2561866 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (34).

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 7 ways as a sum of consecutive naturals, for example, 4885 + ... + 5383.

It is an arithmetic number, because the mean of its divisors is an integer number (256500).

2^2561866 is an apocalyptic number.

2561866 is a deficient number, since it is larger than the sum of its proper divisors (1542134).

2561866 is a wasteful number, since it uses less digits than its factorization.

2561866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669.

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

The square root of 2561866 is about 1600.5830187778. The cubic root of 2561866 is about 136.8313053192.

The spelling of 2561866 in words is "two million, five hundred sixty-one thousand, eight hundred sixty-six".