211666165615 has 4 divisors (see below), whose sum is σ = 253999398744. Its totient is φ = 169332932488.

The previous prime is 211666165609. The next prime is 211666165619. The reversal of 211666165615 is 516561666112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 211666165615 - 2⁵ = 211666165583 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211666165619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21166616557 + ... + 21166616566.

It is an arithmetic number, because the mean of its divisors is an integer number (63499849686).

Almost surely, 2^211666165615 is an apocalyptic number.

211666165615 is a deficient number, since it is larger than the sum of its proper divisors (42333233129).

211666165615 is an equidigital number, since it uses as much as digits as its factorization.

211666165615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42333233128.

The product of its digits is 388800, while the sum is 46.

The spelling of 211666165615 in words is "two hundred eleven billion, six hundred sixty-six million, one hundred sixty-five thousand, six hundred fifteen".