20001221002221 has 16 divisors (see below), whose sum is σ = 27529337295360. Its totient is φ = 12903650242560.

The previous prime is 20001221002187. The next prime is 20001221002247. The reversal of 20001221002221 is 12220012210002.

It is not a de Polignac number, because 20001221002221 - 2⁷ = 20001221002093 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20001221002221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001221002261) 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, 313101 + ... + 6332493.

It is an arithmetic number, because the mean of its divisors is an integer number (1720583580960).

Almost surely, 2^{20001221002221} is an apocalyptic number.

It is an amenable number.

20001221002221 is a deficient number, since it is larger than the sum of its proper divisors (7528116293139).

20001221002221 is a wasteful number, since it uses less digits than its factorization.

20001221002221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6055156.

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 20001221002221 its reverse (12220012210002), we get a palindrome (32221233212223).

The spelling of 20001221002221 in words is "twenty trillion, one billion, two hundred twenty-one million, two thousand, two hundred twenty-one".