21111210221 has 4 divisors (see below), whose sum is σ = 21147175392. Its totient is φ = 21075245052.

The previous prime is 21111210217. The next prime is 21111210223. The reversal of 21111210221 is 12201211112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21111210221 - 2² = 21111210217 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21111210196 and 21111210205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111210223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17981705 + ... + 17982878.

It is an arithmetic number, because the mean of its divisors is an integer number (5286793848).

Almost surely, 2^21111210221 is an apocalyptic number.

It is an amenable number.

21111210221 is a deficient number, since it is larger than the sum of its proper divisors (35965171).

21111210221 is an equidigital number, since it uses as much as digits as its factorization.

21111210221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35965170.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21111210221 its reverse (12201211112), we get a palindrome (33312421333).

The spelling of 21111210221 in words is "twenty-one billion, one hundred eleven million, two hundred ten thousand, two hundred twenty-one".