21110012221 has 4 divisors (see below), whose sum is σ = 21134645532. Its totient is φ = 21085378912.

The previous prime is 21110012197. The next prime is 21110012239. The reversal of 21110012221 is 12221001112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10421347225 + 10688664996 = 102085^2 + 103386^2 .

It is a cyclic number.

It is not a de Polignac number, because 21110012221 - 2²⁵ = 21076457789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21110010221) 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, 12315370 + ... + 12317083.

It is an arithmetic number, because the mean of its divisors is an integer number (5283661383).

Almost surely, 2^21110012221 is an apocalyptic number.

It is an amenable number.

21110012221 is a deficient number, since it is larger than the sum of its proper divisors (24633311).

21110012221 is an equidigital number, since it uses as much as digits as its factorization.

21110012221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24633310.

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

Adding to 21110012221 its reverse (12221001112), we get a palindrome (33331013333).

The spelling of 21110012221 in words is "twenty-one billion, one hundred ten million, twelve thousand, two hundred twenty-one".