20121221220021 has 24 divisors (see below), whose sum is σ = 30617590016000. Its totient is φ = 12698203583232.

The previous prime is 20121221220017. The next prime is 20121221220103. The reversal of 20121221220021 is 12002212212102.

It is a happy number.

20121221220021 is a `hidden beast` number, since 20 + 1 + 212 + 212 + 200 + 21 = 666.

It is not a de Polignac number, because 20121221220021 - 2² = 20121221220017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20121221219976 and 20121221220003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20121221220521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 45781276 + ... + 46218693.

Almost surely, 2^{20121221220021} is an apocalyptic number.

It is an amenable number.

20121221220021 is a deficient number, since it is larger than the sum of its proper divisors (10496368795979).

20121221220021 is a wasteful number, since it uses less digits than its factorization.

20121221220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92001273 (or 92001270 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 20121221220021 its reverse (12002212212102), we get a palindrome (32123433432123).

The spelling of 20121221220021 in words is "twenty trillion, one hundred twenty-one billion, two hundred twenty-one million, two hundred twenty thousand, twenty-one".