21201221121020 has 24 divisors (see below), whose sum is σ = 46057825195200. Its totient is φ = 8188057812032.

The previous prime is 21201221121013. The next prime is 21201221121037. The reversal of 21201221121020 is 2012112210212.

It is a self number, because there is not a number n which added to its sum of digits gives 21201221121020.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18276914180 + ... + 18276915339.

It is an arithmetic number, because the mean of its divisors is an integer number (1919076049800).

Almost surely, 2^{21201221121020} is an apocalyptic number.

21201221121020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21201221121020 is an abundant number, since it is smaller than the sum of its proper divisors (24856604074180).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21201221121020 is a wasteful number, since it uses less digits than its factorization.

21201221121020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36553829557 (or 36553829555 counting only the distinct ones).

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

Adding to 21201221121020 its reverse (2012112210212), we get a palindrome (23213333331232).

The spelling of 21201221121020 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-one million, one hundred twenty-one thousand, twenty".