2561985 has 36 divisors (see below), whose sum is σ = 4741308. Its totient is φ = 1279488.

The previous prime is 2561981. The next prime is 2561987. The reversal of 2561985 is 5891652.

It is a happy number.

2561985 is a `hidden beast` number, since 2 + 561 + 98 + 5 = 666.

2561985 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 6 ways, for example, as 690561 + 1871424 = 831^2 + 1368^2 .

It is not a de Polignac number, because 2561985 - 2² = 2561981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561981) 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 35 ways as a sum of consecutive naturals, for example, 12907 + ... + 13103.

It is an arithmetic number, because the mean of its divisors is an integer number (131703).

2^2561985 is an apocalyptic number.

It is an amenable number.

2561985 is a deficient number, since it is larger than the sum of its proper divisors (2179323).

2561985 is a wasteful number, since it uses less digits than its factorization.

2561985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242 (or 222 counting only the distinct ones).

The product of its digits is 21600, while the sum is 36.

The square root of 2561985 is about 1600.6201923005. The cubic root of 2561985 is about 136.8334239146.

The spelling of 2561985 in words is "two million, five hundred sixty-one thousand, nine hundred eighty-five".