721821859201 has 3 divisors (see below), whose sum is σ = 721822708803. Its totient is φ = 721821009600.

The previous prime is 721821859151. The next prime is 721821859223. The reversal of 721821859201 is 102958128127.

The square root of 721821859201 is 849601.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 102958128127 = 171679 ⋅599713.

It can be written as a sum of positive squares in only one way, i.e., 593514619201 + 128307240000 = 770399^2 + 358200^2 .

It is not a de Polignac number, because 721821859201 - 2²¹ = 721819762049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721821859261) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 424801 + ... + 1274401.

It is an arithmetic number, because the mean of its divisors is an integer number (240607569601).

Almost surely, 2^721821859201 is an apocalyptic number.

721821859201 is the 849601-st square number.

721821859201 is the 424801-st centered octagonal number.

It is an amenable number.

721821859201 is a deficient number, since it is larger than the sum of its proper divisors (849602).

721821859201 is an frugal number, since it uses more digits than its factorization.

721821859201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1699202 (or 849601 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 46.

The spelling of 721821859201 in words is "seven hundred twenty-one billion, eight hundred twenty-one million, eight hundred fifty-nine thousand, two hundred one".