21210202112221 has 4 divisors (see below), whose sum is σ = 22326528539200. Its totient is φ = 20093875685244.

The previous prime is 21210202112189. The next prime is 21210202112237. The reversal of 21210202112221 is 12221120201212.

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 21210202112221 - 2⁵ = 21210202112189 is a prime.

It is a super-3 number, since 3×21210202112221³ (a number of 41 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (19), and also a Moran number because the ratio is a prime number: 1116326426959 = 21210202112221 / (2 + 1 + 2 + 1 + 0 + 2 + 0 + 2 + 1 + 1 + 2 + 2 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210202112251) 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, 558163213461 + ... + 558163213498.

It is an arithmetic number, because the mean of its divisors is an integer number (5581632134800).

Almost surely, 2^{21210202112221} is an apocalyptic number.

It is an amenable number.

21210202112221 is a deficient number, since it is larger than the sum of its proper divisors (1116326426979).

21210202112221 is a wasteful number, since it uses less digits than its factorization.

21210202112221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1116326426978.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21210202112221 its reverse (12221120201212), we get a palindrome (33431322313433).

The spelling of 21210202112221 in words is "twenty-one trillion, two hundred ten billion, two hundred two million, one hundred twelve thousand, two hundred twenty-one".