221205666573 has 12 divisors (see below), whose sum is σ = 328154953308. Its totient is φ = 143484756480.

The previous prime is 221205666569. The next prime is 221205666587. The reversal of 221205666573 is 375666502122.

It can be written as a sum of positive squares in 2 ways, for example, as 153944800164 + 67260866409 = 392358^2 + 259347^2 .

It is not a de Polignac number, because 221205666573 - 2² = 221205666569 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221205668573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 332140308 + ... + 332140973.

It is an arithmetic number, because the mean of its divisors is an integer number (27346246109).

Almost surely, 2^221205666573 is an apocalyptic number.

It is an amenable number.

221205666573 is a deficient number, since it is larger than the sum of its proper divisors (106949286735).

221205666573 is a wasteful number, since it uses less digits than its factorization.

221205666573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 664281324 (or 664281321 counting only the distinct ones).

The product of its (nonzero) digits is 907200, while the sum is 45.

It can be divided in two parts, 221205 and 666573, that added together give a triangular number (887778 = T₁₃₃₂).

The spelling of 221205666573 in words is "two hundred twenty-one billion, two hundred five million, six hundred sixty-six thousand, five hundred seventy-three".