21021012211 has 4 divisors (see below), whose sum is σ = 21023181712. Its totient is φ = 21018842712.

The previous prime is 21021012203. The next prime is 21021012247. The reversal of 21021012211 is 11221012012.

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 21021012211 - 2³ = 21021012203 is a prime.

It is a super-2 number, since 2×21021012211² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021012191 and 21021012200.

It is not an unprimeable number, because it can be changed into a prime (21021012811) 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 3 ways as a sum of consecutive naturals, for example, 1070151 + ... + 1089616.

It is an arithmetic number, because the mean of its divisors is an integer number (5255795428).

Almost surely, 2^21021012211 is an apocalyptic number.

21021012211 is a deficient number, since it is larger than the sum of its proper divisors (2169501).

21021012211 is an equidigital number, since it uses as much as digits as its factorization.

21021012211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2169500.

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

Adding to 21021012211 its reverse (11221012012), we get a palindrome (32242024223).

The spelling of 21021012211 in words is "twenty-one billion, twenty-one million, twelve thousand, two hundred eleven".