2687681 has 4 divisors (see below), whose sum is σ = 2694192. Its totient is φ = 2681172.

The previous prime is 2687677. The next prime is 2687723. The reversal of 2687681 is 1867862.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1867862 = 2 ⋅933931.

It is a cyclic number.

It is not a de Polignac number, because 2687681 - 2² = 2687677 is a prime.

It is a super-2 number, since 2×2687681² = 14447258315522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2687611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2591 + ... + 3476.

It is an arithmetic number, because the mean of its divisors is an integer number (673548).

2^2687681 is an apocalyptic number.

It is an amenable number.

2687681 is a deficient number, since it is larger than the sum of its proper divisors (6511).

2687681 is an equidigital number, since it uses as much as digits as its factorization.

2687681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6510.

The product of its digits is 32256, while the sum is 38.

The square root of 2687681 is about 1639.4148346285. The cubic root of 2687681 is about 139.0355653174.

The spelling of 2687681 in words is "two million, six hundred eighty-seven thousand, six hundred eighty-one".