2565981 has 12 divisors (see below), whose sum is σ = 4043520. Its totient is φ = 1555080.

The previous prime is 2565947. The next prime is 2565989. The reversal of 2565981 is 1895652.

It is a happy number.

2565981 is a `hidden beast` number, since 2 + 565 + 98 + 1 = 666.

It is not a de Polignac number, because 2565981 - 2⁶ = 2565917 is a prime.

It is a super-2 number, since 2×2565981² = 13168516984722, which contains 22 as substring.

It is a Curzon number.

2565981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2565989) 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 11 ways as a sum of consecutive naturals, for example, 12861 + ... + 13058.

It is an arithmetic number, because the mean of its divisors is an integer number (336960).

2^2565981 is an apocalyptic number.

It is an amenable number.

2565981 is a deficient number, since it is larger than the sum of its proper divisors (1477539).

2565981 is a wasteful number, since it uses less digits than its factorization.

2565981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25936 (or 25933 counting only the distinct ones).

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

The square root of 2565981 is about 1601.8679720876. The cubic root of 2565981 is about 136.9045279386.

The spelling of 2565981 in words is "two million, five hundred sixty-five thousand, nine hundred eighty-one".