21221100222221 has 4 divisors (see below), whose sum is σ = 21221122753344. Its totient is φ = 21221077691100.

The previous prime is 21221100222211. The next prime is 21221100222227. The reversal of 21221100222221 is 12222200112212.

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 21221100222221 - 2¹⁸ = 21221099960077 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221100222193 and 21221100222202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221100222227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9788195 + ... + 11758016.

It is an arithmetic number, because the mean of its divisors is an integer number (5305280688336).

Almost surely, 2^{21221100222221} is an apocalyptic number.

It is an amenable number.

21221100222221 is a deficient number, since it is larger than the sum of its proper divisors (22531123).

21221100222221 is an equidigital number, since it uses as much as digits as its factorization.

21221100222221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22531122.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21221100222221 its reverse (12222200112212), we get a palindrome (33443300334433).

The spelling of 21221100222221 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred million, two hundred twenty-two thousand, two hundred twenty-one".