21221002122221 has 16 divisors (see below), whose sum is σ = 23591056854528. Its totient is φ = 18924552004800.

The previous prime is 21221002122217. The next prime is 21221002122227. The reversal of 21221002122221 is 12222120012212.

It is a cyclic number.

It is not a de Polignac number, because 21221002122221 - 2² = 21221002122217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21221002122193 and 21221002122202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221002122227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 233375 + ... + 6518931.

It is an arithmetic number, because the mean of its divisors is an integer number (1474441053408).

Almost surely, 2^{21221002122221} is an apocalyptic number.

It is an amenable number.

21221002122221 is a deficient number, since it is larger than the sum of its proper divisors (2370054732307).

21221002122221 is a wasteful number, since it uses less digits than its factorization.

21221002122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6291412.

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

Adding to 21221002122221 its reverse (12222120012212), we get a palindrome (33443122134433).

The spelling of 21221002122221 in words is "twenty-one trillion, two hundred twenty-one billion, two million, one hundred twenty-two thousand, two hundred twenty-one".