721317663 has 24 divisors (see below), whose sum is σ = 1174602800. Its totient is φ = 437160240.

The previous prime is 721317661. The next prime is 721317679. The reversal of 721317663 is 366713127.

It is not a de Polignac number, because 721317663 - 2¹ = 721317661 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 (721317661) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 107128 + ... + 113661.

Almost surely, 2^721317663 is an apocalyptic number.

721317663 is a deficient number, since it is larger than the sum of its proper divisors (453285137).

721317663 is a wasteful number, since it uses less digits than its factorization.

721317663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220820 (or 220803 counting only the distinct ones).

The product of its digits is 31752, while the sum is 36.

The square root of 721317663 is about 26857.3577069674. The cubic root of 721317663 is about 896.8273736327.

The spelling of 721317663 in words is "seven hundred twenty-one million, three hundred seventeen thousand, six hundred sixty-three".