21221222001221 has 8 divisors (see below), whose sum is σ = 23150770627584. Its totient is φ = 19291731145920.

The previous prime is 21221222001137. The next prime is 21221222001251. The reversal of 21221222001221 is 12210022212212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221222001221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221222001193 and 21221222001202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221222001251) 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, 13672916 + ... + 15145661.

It is an arithmetic number, because the mean of its divisors is an integer number (2893846328448).

Almost surely, 2^{21221222001221} is an apocalyptic number.

It is an amenable number.

21221222001221 is a deficient number, since it is larger than the sum of its proper divisors (1929548626363).

21221222001221 is a wasteful number, since it uses less digits than its factorization.

21221222001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28885531.

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

Adding to 21221222001221 its reverse (12210022212212), we get a palindrome (33431244213433).

The spelling of 21221222001221 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty-two million, one thousand, two hundred twenty-one".