720221 has 2 divisors, whose sum is σ = 720222. Its totient is φ = 720220.

The previous prime is 720211. The next prime is 720229. The reversal of 720221 is 122027.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 657721 + 62500 = 811^2 + 250^2 .

It is an emirp because it is prime and its reverse (122027) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 720221 - 2¹⁰ = 719197 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 720196 and 720205.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 720221.

It is not a weakly prime, because it can be changed into another prime (720229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360110 + 360111.

It is an arithmetic number, because the mean of its divisors is an integer number (360111).

2⁷²⁰²²¹ is an apocalyptic number.

It is an amenable number.

720221 is a deficient number, since it is larger than the sum of its proper divisors (1).

720221 is an equidigital number, since it uses as much as digits as its factorization.

720221 is an evil number, because the sum of its binary digits is even.

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

The square root of 720221 is about 848.6583529313. The cubic root of 720221 is about 89.6372642750.

Adding to 720221 its reverse (122027), we get a palindrome (842248).

The spelling of 720221 in words is "seven hundred twenty thousand, two hundred twenty-one", and thus it is an iban number.