2563681 has 4 divisors (see below), whose sum is σ = 2582532. Its totient is φ = 2544832.

The previous prime is 2563679. The next prime is 2563711. The reversal of 2563681 is 1863652.

2563681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1782225 + 781456 = 1335^2 + 884^2 .

It is a cyclic number.

It is not a de Polignac number, because 2563681 - 2¹ = 2563679 is a prime.

It is a super-2 number, since 2×2563681² = 13144920539522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2563601) 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 3 ways as a sum of consecutive naturals, for example, 9220 + ... + 9493.

It is an arithmetic number, because the mean of its divisors is an integer number (645633).

2^2563681 is an apocalyptic number.

It is an amenable number.

2563681 is a deficient number, since it is larger than the sum of its proper divisors (18851).

2563681 is a wasteful number, since it uses less digits than its factorization.

2563681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18850.

The product of its digits is 8640, while the sum is 31.

The square root of 2563681 is about 1601.1498992911. The cubic root of 2563681 is about 136.8636112234.

The spelling of 2563681 in words is "two million, five hundred sixty-three thousand, six hundred eighty-one".