21020211211 has 4 divisors (see below), whose sum is σ = 21031884424. Its totient is φ = 21008538000.

The previous prime is 21020211209. The next prime is 21020211269. The reversal of 21020211211 is 11211202012.

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 21020211211 - 2¹ = 21020211209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020211191 and 21020211200.

It is not an unprimeable number, because it can be changed into a prime (21020211281) 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, 5833905 + ... + 5837506.

It is an arithmetic number, because the mean of its divisors is an integer number (5257971106).

Almost surely, 2^21020211211 is an apocalyptic number.

21020211211 is a deficient number, since it is larger than the sum of its proper divisors (11673213).

21020211211 is a wasteful number, since it uses less digits than its factorization.

21020211211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11673212.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21020211211 its reverse (11211202012), we get a palindrome (32231413223).

The spelling of 21020211211 in words is "twenty-one billion, twenty million, two hundred eleven thousand, two hundred eleven".