721555201 has 4 divisors (see below), whose sum is σ = 726151252. Its totient is φ = 716959152.

The previous prime is 721555193. The next prime is 721555207. The reversal of 721555201 is 102555127.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 265690000 + 455865201 = 16300^2 + 21351^2 .

It is a cyclic number.

It is not a de Polignac number, because 721555201 - 2³ = 721555193 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721555201.

It is not an unprimeable number, because it can be changed into a prime (721555207) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2297790 + ... + 2298103.

It is an arithmetic number, because the mean of its divisors is an integer number (181537813).

Almost surely, 2^721555201 is an apocalyptic number.

It is an amenable number.

721555201 is a deficient number, since it is larger than the sum of its proper divisors (4596051).

721555201 is a wasteful number, since it uses less digits than its factorization.

721555201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4596050.

The product of its (nonzero) digits is 3500, while the sum is 28.

The square root of 721555201 is about 26861.7795575796. The cubic root of 721555201 is about 896.9258079340.

The spelling of 721555201 in words is "seven hundred twenty-one million, five hundred fifty-five thousand, two hundred one".