21201222222221 has 4 divisors (see below), whose sum is σ = 21201362520000. Its totient is φ = 21201081924444.

The previous prime is 21201222222139. The next prime is 21201222222223. The reversal of 21201222222221 is 12222222210212.

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 21201222222221 - 2³⁰ = 21200148480397 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 (21201222222223) 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, 69921971 + ... + 70224528.

It is an arithmetic number, because the mean of its divisors is an integer number (5300340630000).

Almost surely, 2^{21201222222221} is an apocalyptic number.

It is an amenable number.

21201222222221 is a deficient number, since it is larger than the sum of its proper divisors (140297779).

21201222222221 is a wasteful number, since it uses less digits than its factorization.

21201222222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140297778.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21201222222221 its reverse (12222222210212), we get a palindrome (33423444432433).

The spelling of 21201222222221 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-two million, two hundred twenty-two thousand, two hundred twenty-one".