20011221012221 has 4 divisors (see below), whose sum is σ = 20011253984700. Its totient is φ = 20011188039744.

The previous prime is 20011221012199. The next prime is 20011221012271. The reversal of 20011221012221 is 12221012211002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19557524467321 + 453696544900 = 4422389^2 + 673570^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20011221012221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20011221012221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20011221012271) 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, 15558476 + ... + 16795493.

It is an arithmetic number, because the mean of its divisors is an integer number (5002813496175).

Almost surely, 2^{20011221012221} is an apocalyptic number.

It is an amenable number.

20011221012221 is a deficient number, since it is larger than the sum of its proper divisors (32972479).

20011221012221 is an equidigital number, since it uses as much as digits as its factorization.

20011221012221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32972478.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 20011221012221 its reverse (12221012211002), we get a palindrome (32232233223223).

The spelling of 20011221012221 in words is "twenty trillion, eleven billion, two hundred twenty-one million, twelve thousand, two hundred twenty-one".