21121020221 has 12 divisors (see below), whose sum is σ = 25637584032. Its totient is φ = 17316611928.

The previous prime is 21121020211. The next prime is 21121020229. The reversal of 21121020221 is 12202012112.

It is not a de Polignac number, because 21121020221 - 2⁶ = 21121020157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121020196 and 21121020205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121020229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9369335 + ... + 9371588.

It is an arithmetic number, because the mean of its divisors is an integer number (2136465336).

Almost surely, 2^21121020221 is an apocalyptic number.

It is an amenable number.

21121020221 is a deficient number, since it is larger than the sum of its proper divisors (4516563811).

21121020221 is a wasteful number, since it uses less digits than its factorization.

21121020221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18740960 (or 18740953 counting only the distinct ones).

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

Adding to 21121020221 its reverse (12202012112), we get a palindrome (33323032333).

The spelling of 21121020221 in words is "twenty-one billion, one hundred twenty-one million, twenty thousand, two hundred twenty-one".