21110212221 has 16 divisors (see below), whose sum is σ = 32468580864. Its totient is φ = 11950239024.

The previous prime is 21110212217. The next prime is 21110212271. The reversal of 21110212221 is 12221201112.

It is not a de Polignac number, because 21110212221 - 2² = 21110212217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21110212221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21110212271) 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 15 ways as a sum of consecutive naturals, for example, 4695175 + ... + 4699668.

It is an arithmetic number, because the mean of its divisors is an integer number (2029286304).

Almost surely, 2^21110212221 is an apocalyptic number.

21110212221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21110212221 is a deficient number, since it is larger than the sum of its proper divisors (11358368643).

21110212221 is a wasteful number, since it uses less digits than its factorization.

21110212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9394960.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21110212221 its reverse (12221201112), we get a palindrome (33331413333).

The spelling of 21110212221 in words is "twenty-one billion, one hundred ten million, two hundred twelve thousand, two hundred twenty-one".