2643721 has 8 divisors (see below), whose sum is σ = 2868264. Its totient is φ = 2426880.

The previous prime is 2643713. The next prime is 2643733. The reversal of 2643721 is 1273462.

It can be written as a sum of positive squares in 4 ways, for example, as 19321 + 2624400 = 139^2 + 1620^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2643721 - 2³ = 2643713 is a prime.

It is a d-powerful number, because it can be written as 2¹⁹ + 6⁴ + 4⁶ + 3⁴ + 7⁵ + 2²¹ + 1 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2643791) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1200 + ... + 2593.

It is an arithmetic number, because the mean of its divisors is an integer number (358533).

2^2643721 is an apocalyptic number.

It is an amenable number.

2643721 is a deficient number, since it is larger than the sum of its proper divisors (224543).

2643721 is a wasteful number, since it uses less digits than its factorization.

2643721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3851.

The product of its digits is 2016, while the sum is 25.

The square root of 2643721 is about 1625.9523363248. The cubic root of 2643721 is about 138.2733676644.

It can be divided in two parts, 2643 and 721, that added together give a square (3364 = 58²).

The spelling of 2643721 in words is "two million, six hundred forty-three thousand, seven hundred twenty-one".