721340717 has 2 divisors, whose sum is σ = 721340718. Its totient is φ = 721340716.

The previous prime is 721340713. The next prime is 721340729. The reversal of 721340717 is 717043127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 721137316 + 203401 = 26854^2 + 451^2 .

It is an emirp because it is prime and its reverse (717043127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721340717 - 2² = 721340713 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721340713) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360670358 + 360670359.

It is an arithmetic number, because the mean of its divisors is an integer number (360670359).

Almost surely, 2^721340717 is an apocalyptic number.

It is an amenable number.

721340717 is a deficient number, since it is larger than the sum of its proper divisors (1).

721340717 is an equidigital number, since it uses as much as digits as its factorization.

721340717 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8232, while the sum is 32.

The square root of 721340717 is about 26857.7868969132. The cubic root of 721340717 is about 896.8369280168.

The spelling of 721340717 in words is "seven hundred twenty-one million, three hundred forty thousand, seven hundred seventeen".