2121203200021 has 4 divisors (see below), whose sum is σ = 2122413243532. Its totient is φ = 2119993156512.

The previous prime is 2121203199953. The next prime is 2121203200073. The reversal of 2121203200021 is 1200023021212.

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 161133199396 + 1960070000625 = 401414^2 + 1400025^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121203200021 - 2⁹ = 2121203199509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121203199968 and 2121203200004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121203200321) 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, 605019126 + ... + 605022631.

It is an arithmetic number, because the mean of its divisors is an integer number (530603310883).

Almost surely, 2^{2121203200021} is an apocalyptic number.

It is an amenable number.

2121203200021 is a deficient number, since it is larger than the sum of its proper divisors (1210043511).

2121203200021 is a wasteful number, since it uses less digits than its factorization.

2121203200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1210043510.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 2121203200021 its reverse (1200023021212), we get a palindrome (3321226221233).

The spelling of 2121203200021 in words is "two trillion, one hundred twenty-one billion, two hundred three million, two hundred thousand, twenty-one".