2561644 has 6 divisors (see below), whose sum is σ = 4482884. Its totient is φ = 1280820.

The previous prime is 2561633. The next prime is 2561651. The reversal of 2561644 is 4461652.

2561644 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×2561644³ = 50428677349967333952, which contains 333 as substring.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 320202 + ... + 320209.

2^2561644 is an apocalyptic number.

It is an amenable number.

2561644 is a deficient number, since it is larger than the sum of its proper divisors (1921240).

2561644 is a wasteful number, since it uses less digits than its factorization.

2561644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640415 (or 640413 counting only the distinct ones).

The product of its digits is 5760, while the sum is 28.

The square root of 2561644 is about 1600.5136675455. The cubic root of 2561644 is about 136.8273528060.

The spelling of 2561644 in words is "two million, five hundred sixty-one thousand, six hundred forty-four".