211671301661 has 4 divisors (see below), whose sum is σ = 211740910524. Its totient is φ = 211601692800.

The previous prime is 211671301657. The next prime is 211671301727. The reversal of 211671301661 is 166103176112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 204479413636 + 7191888025 = 452194^2 + 84805^2 .

It is a cyclic number.

It is not a de Polignac number, because 211671301661 - 2² = 211671301657 is a prime.

It is a super-2 number, since 2×211671301661² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211671301601) 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, 34799870 + ... + 34805951.

It is an arithmetic number, because the mean of its divisors is an integer number (52935227631).

Almost surely, 2^211671301661 is an apocalyptic number.

It is an amenable number.

211671301661 is a deficient number, since it is larger than the sum of its proper divisors (69608863).

211671301661 is an equidigital number, since it uses as much as digits as its factorization.

211671301661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69608862.

The product of its (nonzero) digits is 9072, while the sum is 35.

Adding to 211671301661 its reverse (166103176112), we get a palindrome (377774477773).

The spelling of 211671301661 in words is "two hundred eleven billion, six hundred seventy-one million, three hundred one thousand, six hundred sixty-one".