21102111221 has 4 divisors (see below), whose sum is σ = 21106736352. Its totient is φ = 21097486092.

The previous prime is 21102111187. The next prime is 21102111223. The reversal of 21102111221 is 12211120112.

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 21102111221 - 2⁶ = 21102111157 is a prime.

It is a super-2 number, since 2×21102111221² (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 = 21102111196 and 21102111205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102111223) 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, 2305715 + ... + 2314848.

It is an arithmetic number, because the mean of its divisors is an integer number (5276684088).

Almost surely, 2^21102111221 is an apocalyptic number.

It is an amenable number.

21102111221 is a deficient number, since it is larger than the sum of its proper divisors (4625131).

21102111221 is an equidigital number, since it uses as much as digits as its factorization.

21102111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4625130.

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

Adding to 21102111221 its reverse (12211120112), we get a palindrome (33313231333).

The spelling of 21102111221 in words is "twenty-one billion, one hundred two million, one hundred eleven thousand, two hundred twenty-one".