721601 has 8 divisors (see below), whose sum is σ = 767520. Its totient is φ = 676512.

The previous prime is 721597. The next prime is 721613. The reversal of 721601 is 106127.

It is a happy number.

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 721601 - 2² = 721597 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 721601.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721601.

It is not an unprimeable number, because it can be changed into a prime (721621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2981 + ... + 3213.

It is an arithmetic number, because the mean of its divisors is an integer number (95940).

2⁷²¹⁶⁰¹ is an apocalyptic number.

It is an amenable number.

721601 is a deficient number, since it is larger than the sum of its proper divisors (45919).

721601 is a wasteful number, since it uses less digits than its factorization.

721601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 721601 is about 849.4710118656. The cubic root of 721601 is about 89.6944784277.

Adding to 721601 its reverse (106127), we get a palindrome (827728).

The spelling of 721601 in words is "seven hundred twenty-one thousand, six hundred one".