21211656161 has 8 divisors (see below), whose sum is σ = 21563069280. Its totient is φ = 20861267328.

The previous prime is 21211656149. The next prime is 21211656181. The reversal of 21211656161 is 16165611212.

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

It is a cyclic number.

It is not a de Polignac number, because 21211656161 - 2¹⁰ = 21211655137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211656121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 214256 + ... + 297201.

It is an arithmetic number, because the mean of its divisors is an integer number (2695383660).

Almost surely, 2^21211656161 is an apocalyptic number.

It is an amenable number.

21211656161 is a deficient number, since it is larger than the sum of its proper divisors (351413119).

21211656161 is an equidigital number, since it uses as much as digits as its factorization.

21211656161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512143.

The product of its digits is 4320, while the sum is 32.

The spelling of 21211656161 in words is "twenty-one billion, two hundred eleven million, six hundred fifty-six thousand, one hundred sixty-one".