21203113021021 has 4 divisors (see below), whose sum is σ = 22450354963452. Its totient is φ = 19955871078592.

The previous prime is 21203113021003. The next prime is 21203113021109. The reversal of 21203113021021 is 12012031130212.

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 15180849780121 + 6022263240900 = 3896261^2 + 2454030^2 .

It is a cyclic number.

It is not a de Polignac number, because 21203113021021 - 2¹¹ = 21203113018973 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21203113021021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203113021921) 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, 623620971190 + ... + 623620971223.

It is an arithmetic number, because the mean of its divisors is an integer number (5612588740863).

Almost surely, 2^{21203113021021} is an apocalyptic number.

It is an amenable number.

21203113021021 is a deficient number, since it is larger than the sum of its proper divisors (1247241942431).

21203113021021 is a wasteful number, since it uses less digits than its factorization.

21203113021021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1247241942430.

The product of its (nonzero) digits is 144, while the sum is 19.

Adding to 21203113021021 its reverse (12012031130212), we get a palindrome (33215144151233).

The spelling of 21203113021021 in words is "twenty-one trillion, two hundred three billion, one hundred thirteen million, twenty-one thousand, twenty-one".