21120221200021 has 4 divisors (see below), whose sum is σ = 21140907020044. Its totient is φ = 21099535380000.

The previous prime is 21120221199983. The next prime is 21120221200033. The reversal of 21120221200021 is 12000212202112.

It is a happy number.

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 9710789693796 + 11409431506225 = 3116214^2 + 3377785^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120221200021 - 2³¹ = 21118073716373 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120221199968 and 21120221200004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120221210021) 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, 10342908480 + ... + 10342910521.

It is an arithmetic number, because the mean of its divisors is an integer number (5285226755011).

Almost surely, 2^{21120221200021} is an apocalyptic number.

It is an amenable number.

21120221200021 is a deficient number, since it is larger than the sum of its proper divisors (20685820023).

21120221200021 is a wasteful number, since it uses less digits than its factorization.

21120221200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20685820022.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21120221200021 its reverse (12000212202112), we get a palindrome (33120433402133).

The spelling of 21120221200021 in words is "twenty-one trillion, one hundred twenty billion, two hundred twenty-one million, two hundred thousand, twenty-one".