21210111221 has 8 divisors (see below), whose sum is σ = 22876971264. Its totient is φ = 19548295920.

The previous prime is 21210111173. The next prime is 21210111229. The reversal of 21210111221 is 12211101212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21210111221 - 2¹⁴ = 21210094837 is a prime.

It is a super-2 number, since 2×21210111221² (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 = 21210111196 and 21210111205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210111229) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1252445 + ... + 1269266.

It is an arithmetic number, because the mean of its divisors is an integer number (2859621408).

Almost surely, 2^21210111221 is an apocalyptic number.

It is an amenable number.

21210111221 is a deficient number, since it is larger than the sum of its proper divisors (1666860043).

21210111221 is a wasteful number, since it uses less digits than its factorization.

21210111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2522371.

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

Adding to 21210111221 its reverse (12211101212), we get a palindrome (33421212433).

It can be divided in two parts, 212101 and 11221, that added together give a palindrome (223322).

The spelling of 21210111221 in words is "twenty-one billion, two hundred ten million, one hundred eleven thousand, two hundred twenty-one".