721668017 has 8 divisors (see below), whose sum is σ = 847054656. Its totient is φ = 601854192.

The previous prime is 721667971. The next prime is 721668023. The reversal of 721668017 is 710866127.

721668017 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721668017 - 2⁸ = 721667761 is a prime.

It is a super-3 number, since 3×721668017³ (a number of 28 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (721668047) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1392923 + ... + 1393440.

It is an arithmetic number, because the mean of its divisors is an integer number (105881832).

Almost surely, 2^721668017 is an apocalyptic number.

It is an amenable number.

721668017 is a deficient number, since it is larger than the sum of its proper divisors (125386639).

721668017 is a wasteful number, since it uses less digits than its factorization.

721668017 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2786407.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 721668017 is about 26863.8794108371. The cubic root of 721668017 is about 896.9725506312.

The spelling of 721668017 in words is "seven hundred twenty-one million, six hundred sixty-eight thousand, seventeen".