4028721 has 4 divisors (see below), whose sum is σ = 5371632. Its totient is φ = 2685812.

The previous prime is 4028707. The next prime is 4028723. The reversal of 4028721 is 1278204.

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 not a de Polignac number, because 4028721 - 2¹⁰ = 4027697 is a prime.

It is an Ulam number.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 4028691 and 4028700.

It is not an unprimeable number, because it can be changed into a prime (4028723) 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, 671451 + ... + 671456.

It is an arithmetic number, because the mean of its divisors is an integer number (1342908).

Almost surely, 2^4028721 is an apocalyptic number.

It is an amenable number.

4028721 is a deficient number, since it is larger than the sum of its proper divisors (1342911).

4028721 is a wasteful number, since it uses less digits than its factorization.

4028721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1342910.

The product of its (nonzero) digits is 896, while the sum is 24.

The square root of 4028721 is about 2007.1674070690. The cubic root of 4028721 is about 159.1191306867.

The spelling of 4028721 in words is "four million, twenty-eight thousand, seven hundred twenty-one".