21012021211 has 4 divisors (see below), whose sum is σ = 21299857192. Its totient is φ = 20724185232.

The previous prime is 21012021209. The next prime is 21012021221. The reversal of 21012021211 is 11212021012.

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 21012021211 - 2¹ = 21012021209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012021191 and 21012021200.

It is not an unprimeable number, because it can be changed into a prime (21012021221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 143917881 + ... + 143918026.

It is an arithmetic number, because the mean of its divisors is an integer number (5324964298).

Almost surely, 2^21012021211 is an apocalyptic number.

21012021211 is a deficient number, since it is larger than the sum of its proper divisors (287835981).

21012021211 is an equidigital number, since it uses as much as digits as its factorization.

21012021211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287835980.

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

Adding to 21012021211 its reverse (11212021012), we get a palindrome (32224042223).

The spelling of 21012021211 in words is "twenty-one billion, twelve million, twenty-one thousand, two hundred eleven".