21431020211 has 4 divisors (see below), whose sum is σ = 21445433952. Its totient is φ = 21416606472.

The previous prime is 21431020183. The next prime is 21431020249. The reversal of 21431020211 is 11202013412.

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 21431020211 - 2²⁶ = 21363911347 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21431020211.

It is not an unprimeable number, because it can be changed into a prime (21431020291) 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, 7204640 + ... + 7207613.

It is an arithmetic number, because the mean of its divisors is an integer number (5361358488).

Almost surely, 2^21431020211 is an apocalyptic number.

21431020211 is a deficient number, since it is larger than the sum of its proper divisors (14413741).

21431020211 is a wasteful number, since it uses less digits than its factorization.

21431020211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14413740.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21431020211 its reverse (11202013412), we get a palindrome (32633033623).

The spelling of 21431020211 in words is "twenty-one billion, four hundred thirty-one million, twenty thousand, two hundred eleven".