20021100021221 has 4 divisors (see below), whose sum is σ = 21561184638252. Its totient is φ = 18481015404192.

The previous prime is 20021100021203. The next prime is 20021100021257. The reversal of 20021100021221 is 12212000112002.

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 2375639598721 + 17645460422500 = 1541311^2 + 4200650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20021100021221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021100021196 and 20021100021205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021100021721) 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, 770042308496 + ... + 770042308521.

It is an arithmetic number, because the mean of its divisors is an integer number (5390296159563).

Almost surely, 2^{20021100021221} is an apocalyptic number.

It is an amenable number.

20021100021221 is a deficient number, since it is larger than the sum of its proper divisors (1540084617031).

20021100021221 is a wasteful number, since it uses less digits than its factorization.

20021100021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1540084617030.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 20021100021221 its reverse (12212000112002), we get a palindrome (32233100133223).

The spelling of 20021100021221 in words is "twenty trillion, twenty-one billion, one hundred million, twenty-one thousand, two hundred twenty-one".