20011212221221 has 4 divisors (see below), whose sum is σ = 21550536238252. Its totient is φ = 18471888204192.

The previous prime is 20011212221213. The next prime is 20011212221251. The reversal of 20011212221221 is 12212221211002.

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 11358854684100 + 8652357537121 = 3370290^2 + 2941489^2 .

It is a cyclic number.

It is not a de Polignac number, because 20011212221221 - 2³ = 20011212221213 is a prime.

It is a super-2 number, since 2×20011212221221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20011212221251) 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, 769662008496 + ... + 769662008521.

It is an arithmetic number, because the mean of its divisors is an integer number (5387634059563).

Almost surely, 2^{20011212221221} is an apocalyptic number.

It is an amenable number.

20011212221221 is a deficient number, since it is larger than the sum of its proper divisors (1539324017031).

20011212221221 is a wasteful number, since it uses less digits than its factorization.

20011212221221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1539324017030.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 20011212221221 its reverse (12212221211002), we get a palindrome (32223433432223).

The spelling of 20011212221221 in words is "twenty trillion, eleven billion, two hundred twelve million, two hundred twenty-one thousand, two hundred twenty-one".