721317239 has 2 divisors, whose sum is σ = 721317240. Its totient is φ = 721317238.

The previous prime is 721317229. The next prime is 721317323. The reversal of 721317239 is 932713127.

It is a weak prime.

It is an emirp because it is prime and its reverse (932713127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721317239 - 2²⁸ = 452881783 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 721317199 and 721317208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721317209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360658619 + 360658620.

It is an arithmetic number, because the mean of its divisors is an integer number (360658620).

Almost surely, 2^721317239 is an apocalyptic number.

721317239 is a deficient number, since it is larger than the sum of its proper divisors (1).

721317239 is an equidigital number, since it uses as much as digits as its factorization.

721317239 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15876, while the sum is 35.

The square root of 721317239 is about 26857.3498134123. The cubic root of 721317239 is about 896.8271979104.

The spelling of 721317239 in words is "seven hundred twenty-one million, three hundred seventeen thousand, two hundred thirty-nine".