720737221 has 2 divisors, whose sum is σ = 720737222. Its totient is φ = 720737220.

The previous prime is 720737209. The next prime is 720737239. The reversal of 720737221 is 122737027.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 372914721 + 347822500 = 19311^2 + 18650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-720737221 is a prime.

It is equal to p_37270327 and since 720737221 and 37270327 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (720747221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360368610 + 360368611.

It is an arithmetic number, because the mean of its divisors is an integer number (360368611).

Almost surely, 2^720737221 is an apocalyptic number.

It is an amenable number.

720737221 is a deficient number, since it is larger than the sum of its proper divisors (1).

720737221 is an equidigital number, since it uses as much as digits as its factorization.

720737221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8232, while the sum is 31.

The square root of 720737221 is about 26846.5495175823. The cubic root of 720737221 is about 896.5867510455.

The spelling of 720737221 in words is "seven hundred twenty million, seven hundred thirty-seven thousand, two hundred twenty-one".