7221509 has 2 divisors, whose sum is σ = 7221510. Its totient is φ = 7221508.

The previous prime is 7221499. The next prime is 7221523. The reversal of 7221509 is 9051227.

7221509 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4060225 + 3161284 = 2015^2 + 1778^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7221509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7221569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3610754 + 3610755.

It is an arithmetic number, because the mean of its divisors is an integer number (3610755).

Almost surely, 2^7221509 is an apocalyptic number.

It is an amenable number.

7221509 is a deficient number, since it is larger than the sum of its proper divisors (1).

7221509 is an equidigital number, since it uses as much as digits as its factorization.

7221509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 7221509 is about 2687.2865496631. The cubic root of 7221509 is about 193.2899701267.

The spelling of 7221509 in words is "seven million, two hundred twenty-one thousand, five hundred nine".