211206161721 has 8 divisors (see below), whose sum is σ = 290692351744. Its totient is φ = 136262039760.

The previous prime is 211206161711. The next prime is 211206161737. The reversal of 211206161721 is 127161602112.

211206161721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 211206161721 - 2²¹ = 211204064569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (211206161711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1135516906 + ... + 1135517091.

It is an arithmetic number, because the mean of its divisors is an integer number (36336543968).

Almost surely, 2^211206161721 is an apocalyptic number.

It is an amenable number.

211206161721 is a deficient number, since it is larger than the sum of its proper divisors (79486190023).

211206161721 is a wasteful number, since it uses less digits than its factorization.

211206161721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2271034031.

The product of its (nonzero) digits is 2016, while the sum is 30.

Adding to 211206161721 its reverse (127161602112), we get a palindrome (338367763833).

The spelling of 211206161721 in words is "two hundred eleven billion, two hundred six million, one hundred sixty-one thousand, seven hundred twenty-one".