721656065 has 8 divisors (see below), whose sum is σ = 932601768. Its totient is φ = 532915200.

The previous prime is 721656059. The next prime is 721656077. The reversal of 721656065 is 560656127.

It can be written as a sum of positive squares in 4 ways, for example, as 4648336 + 717007729 = 2156^2 + 26777^2 .

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

It is not a de Polignac number, because 721656065 - 2⁴ = 721656049 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5551136 + ... + 5551265.

It is an arithmetic number, because the mean of its divisors is an integer number (116575221).

Almost surely, 2^721656065 is an apocalyptic number.

It is an amenable number.

721656065 is a deficient number, since it is larger than the sum of its proper divisors (210945703).

721656065 is a wasteful number, since it uses less digits than its factorization.

721656065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11102419.

The product of its (nonzero) digits is 75600, while the sum is 38.

The square root of 721656065 is about 26863.6569550759. The cubic root of 721656065 is about 896.9675988275.

The spelling of 721656065 in words is "seven hundred twenty-one million, six hundred fifty-six thousand, sixty-five".