2005721 has 4 divisors (see below), whose sum is σ = 2016000. Its totient is φ = 1995444.

The previous prime is 2005693. The next prime is 2005723. The reversal of 2005721 is 1275002.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2005721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 2005721.

It is not an unprimeable number, because it can be changed into a prime (2005723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4841 + ... + 5238.

It is an arithmetic number, because the mean of its divisors is an integer number (504000).

2^2005721 is an apocalyptic number.

It is an amenable number.

2005721 is a deficient number, since it is larger than the sum of its proper divisors (10279).

2005721 is a wasteful number, since it uses less digits than its factorization.

2005721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10278.

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 2005721 is about 1416.2347969175. The cubic root of 2005721 is about 126.1121240960.

The spelling of 2005721 in words is "two million, five thousand, seven hundred twenty-one".