721720717 has 8 divisors (see below), whose sum is σ = 738982656. Its totient is φ = 704649792.

The previous prime is 721720693. The next prime is 721720733. The reversal of 721720717 is 717027127.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721720717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721720777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40093 + ... + 55234.

It is an arithmetic number, because the mean of its divisors is an integer number (92372832).

Almost surely, 2^721720717 is an apocalyptic number.

It is an amenable number.

721720717 is a deficient number, since it is larger than the sum of its proper divisors (17261939).

721720717 is a wasteful number, since it uses less digits than its factorization.

721720717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95507.

The product of its (nonzero) digits is 9604, while the sum is 34.

The square root of 721720717 is about 26864.8602639210. The cubic root of 721720717 is about 896.9943839866.

The spelling of 721720717 in words is "seven hundred twenty-one million, seven hundred twenty thousand, seven hundred seventeen".