7228721 has 4 divisors (see below), whose sum is σ = 7609200. Its totient is φ = 6848244.

The previous prime is 7228717. The next prime is 7228729. The reversal of 7228721 is 1278227.

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 7228721 - 2² = 7228717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7228729) 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, 190211 + ... + 190248.

It is an arithmetic number, because the mean of its divisors is an integer number (1902300).

Almost surely, 2^7228721 is an apocalyptic number.

It is an amenable number.

7228721 is a deficient number, since it is larger than the sum of its proper divisors (380479).

7228721 is a wasteful number, since it uses less digits than its factorization.

7228721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 380478.

The product of its digits is 3136, while the sum is 29.

The square root of 7228721 is about 2688.6280888215. The cubic root of 7228721 is about 193.3542938696.

The spelling of 7228721 in words is "seven million, two hundred twenty-eight thousand, seven hundred twenty-one".