720223021621 has 2 divisors, whose sum is σ = 720223021622. Its totient is φ = 720223021620.

The previous prime is 720223021559. The next prime is 720223021643. The reversal of 720223021621 is 126120322027.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 664084827396 + 56138194225 = 814914^2 + 236935^2 .

It is a cyclic number.

It is not a de Polignac number, because 720223021621 - 2¹⁷ = 720222890549 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 720223021621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (720223021121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360111510810 + 360111510811.

It is an arithmetic number, because the mean of its divisors is an integer number (360111510811).

Almost surely, 2^720223021621 is an apocalyptic number.

It is an amenable number.

720223021621 is a deficient number, since it is larger than the sum of its proper divisors (1).

720223021621 is an equidigital number, since it uses as much as digits as its factorization.

720223021621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 28.

Adding to 720223021621 its reverse (126120322027), we get a palindrome (846343343648).

The spelling of 720223021621 in words is "seven hundred twenty billion, two hundred twenty-three million, twenty-one thousand, six hundred twenty-one".