2891681 has 4 divisors (see below), whose sum is σ = 3114132. Its totient is φ = 2669232.

The previous prime is 2891671. The next prime is 2891687. The reversal of 2891681 is 1861982.

2891681 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, and also an emirpimes, since its reverse is a distinct semiprime: 1861982 = 2 ⋅930991.

It can be written as a sum of positive squares in 2 ways, for example, as 379456 + 2512225 = 616^2 + 1585^2 .

It is a cyclic number.

It is not a de Polignac number, because 2891681 - 2¹⁸ = 2629537 is a prime.

It is a super-2 number, since 2×2891681² = 16723638011522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2891687) 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, 111206 + ... + 111231.

It is an arithmetic number, because the mean of its divisors is an integer number (778533).

2^2891681 is an apocalyptic number.

It is an amenable number.

2891681 is a deficient number, since it is larger than the sum of its proper divisors (222451).

2891681 is a wasteful number, since it uses less digits than its factorization.

2891681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222450.

The product of its digits is 6912, while the sum is 35.

The square root of 2891681 is about 1700.4943398906. The cubic root of 2891681 is about 142.4678248892.

It can be divided in two parts, 289 and 1681, that multiplied together give a square (485809 = 697²).

The spelling of 2891681 in words is "two million, eight hundred ninety-one thousand, six hundred eighty-one".