665201728801 has 3 divisors (see below), whose sum is σ = 665202544401. Its totient is φ = 665200913202.

The previous prime is 665201728799. The next prime is 665201728843. The reversal of 665201728801 is 108827102566.

The square root of 665201728801 is 815599.

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.

It is not a de Polignac number, because 665201728801 - 2¹ = 665201728799 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665201728001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 407800 + ... + 1223398.

It is an arithmetic number, because the mean of its divisors is an integer number (221734181467).

Almost surely, 2^665201728801 is an apocalyptic number.

665201728801 is the 815599-th square number.

665201728801 is the 407800-th centered octagonal number.

It is an amenable number.

665201728801 is a deficient number, since it is larger than the sum of its proper divisors (815600).

665201728801 is an frugal number, since it uses more digits than its factorization.

665201728801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1631198 (or 815599 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 46.

The spelling of 665201728801 in words is "six hundred sixty-five billion, two hundred one million, seven hundred twenty-eight thousand, eight hundred one".