4000721 has 4 divisors (see below), whose sum is σ = 4008000. Its totient is φ = 3993444.

The previous prime is 4000709. The next prime is 4000723. The reversal of 4000721 is 1270004.

It is a happy number.

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-4000721 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 4000696 and 4000705.

It is not an unprimeable number, because it can be changed into a prime (4000723) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2741 + ... + 3938.

It is an arithmetic number, because the mean of its divisors is an integer number (1002000).

Almost surely, 2^4000721 is an apocalyptic number.

It is an amenable number.

4000721 is a deficient number, since it is larger than the sum of its proper divisors (7279).

4000721 is an equidigital number, since it uses as much as digits as its factorization.

4000721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7278.

The product of its (nonzero) digits is 56, while the sum is 14.

The square root of 4000721 is about 2000.1802418782. The cubic root of 4000721 is about 158.7496422585.

Adding to 4000721 its reverse (1270004), we get a palindrome (5270725).

The spelling of 4000721 in words is "four million, seven hundred twenty-one", and thus it is an aban number.