2687721 has 16 divisors (see below), whose sum is σ = 3839040. Its totient is φ = 1667520.

The previous prime is 2687677. The next prime is 2687723. The reversal of 2687721 is 1277862.

2687721 is a nontrivial binomial coefficient, being equal to C(2319, 2).

It is not a de Polignac number, because 2687721 - 2⁷ = 2687593 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2687723) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3091 + ... + 3863.

It is an arithmetic number, because the mean of its divisors is an integer number (239940).

2^2687721 is an apocalyptic number.

2687721 is the 2318-th triangular number.

It is an amenable number.

2687721 is a deficient number, since it is larger than the sum of its proper divisors (1151319).

2687721 is a wasteful number, since it uses less digits than its factorization.

2687721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 856.

The product of its digits is 9408, while the sum is 33.

The square root of 2687721 is about 1639.4270340579. The cubic root of 2687721 is about 139.0362550564.

The spelling of 2687721 in words is "two million, six hundred eighty-seven thousand, seven hundred twenty-one".