720017321 has 4 divisors (see below), whose sum is σ = 722475012. Its totient is φ = 717559632.

The previous prime is 720017279. The next prime is 720017339. The reversal of 720017321 is 123710027.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 701190400 + 18826921 = 26480^2 + 4339^2 .

It is a cyclic number.

It is not a de Polignac number, because 720017321 - 2¹⁴ = 720000937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (720017351) 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 in 3 ways as a sum of consecutive naturals, for example, 1228406 + ... + 1228991.

It is an arithmetic number, because the mean of its divisors is an integer number (180618753).

Almost surely, 2^720017321 is an apocalyptic number.

It is an amenable number.

720017321 is a deficient number, since it is larger than the sum of its proper divisors (2457691).

720017321 is a wasteful number, since it uses less digits than its factorization.

720017321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2457690.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 720017321 is about 26833.1384858350. The cubic root of 720017321 is about 896.2881365141.

Adding to 720017321 its reverse (123710027), we get a palindrome (843727348).

The spelling of 720017321 in words is "seven hundred twenty million, seventeen thousand, three hundred twenty-one".