211666949861 has 2 divisors, whose sum is σ = 211666949862. Its totient is φ = 211666949860.

The previous prime is 211666949843. The next prime is 211666949873. The reversal of 211666949861 is 168949666112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 211421557636 + 245392225 = 459806^2 + 15665^2 .

It is a cyclic number.

It is not a de Polignac number, because 211666949861 - 2⁶ = 211666949797 is a prime.

It is a super-3 number, since 3×211666949861³ (a number of 35 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 211666949861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211666949261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105833474930 + 105833474931.

It is an arithmetic number, because the mean of its divisors is an integer number (105833474931).

Almost surely, 2^211666949861 is an apocalyptic number.

It is an amenable number.

211666949861 is a deficient number, since it is larger than the sum of its proper divisors (1).

211666949861 is an equidigital number, since it uses as much as digits as its factorization.

211666949861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6718464, while the sum is 59.

The spelling of 211666949861 in words is "two hundred eleven billion, six hundred sixty-six million, nine hundred forty-nine thousand, eight hundred sixty-one".