211665573521 has 2 divisors, whose sum is σ = 211665573522. Its totient is φ = 211665573520.

The previous prime is 211665573499. The next prime is 211665573533. The reversal of 211665573521 is 125375566112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147848709121 + 63816864400 = 384511^2 + 252620^2 .

It is a cyclic number.

It is not a de Polignac number, because 211665573521 - 2¹⁰ = 211665572497 is a prime.

It is not a weakly prime, because it can be changed into another prime (211665573541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105832786760 + 105832786761.

It is an arithmetic number, because the mean of its divisors is an integer number (105832786761).

Almost surely, 2^211665573521 is an apocalyptic number.

It is an amenable number.

211665573521 is a deficient number, since it is larger than the sum of its proper divisors (1).

211665573521 is an equidigital number, since it uses as much as digits as its factorization.

211665573521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 378000, while the sum is 44.

The spelling of 211665573521 in words is "two hundred eleven billion, six hundred sixty-five million, five hundred seventy-three thousand, five hundred twenty-one".