721319017 has 2 divisors, whose sum is σ = 721319018. Its totient is φ = 721319016.

The previous prime is 721319009. The next prime is 721319047. The reversal of 721319017 is 710913127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 660541401 + 60777616 = 25701^2 + 7796^2 .

It is a cyclic number.

It is not a de Polignac number, because 721319017 - 2³ = 721319009 is a prime.

It is a super-2 number, since 2×721319017² = 1040602248571692578, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721319017.

It is not a weakly prime, because it can be changed into another prime (721319047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360659508 + 360659509.

It is an arithmetic number, because the mean of its divisors is an integer number (360659509).

Almost surely, 2^721319017 is an apocalyptic number.

It is an amenable number.

721319017 is a deficient number, since it is larger than the sum of its proper divisors (1).

721319017 is an equidigital number, since it uses as much as digits as its factorization.

721319017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2646, while the sum is 31.

The square root of 721319017 is about 26857.3829142007. The cubic root of 721319017 is about 896.8279347833.

The spelling of 721319017 in words is "seven hundred twenty-one million, three hundred nineteen thousand, seventeen".