21001120202021 has 4 divisors (see below), whose sum is σ = 21001251050412. Its totient is φ = 21000989353632.

The previous prime is 21001120202009. The next prime is 21001120202159. The reversal of 21001120202021 is 12020202110012.

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 17765474737921 + 3235645464100 = 4214911^2 + 1798790^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001120202021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001120201987 and 21001120202005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001120204021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65183150 + ... + 65504543.

It is an arithmetic number, because the mean of its divisors is an integer number (5250312762603).

Almost surely, 2^{21001120202021} is an apocalyptic number.

It is an amenable number.

21001120202021 is a deficient number, since it is larger than the sum of its proper divisors (130848391).

21001120202021 is a wasteful number, since it uses less digits than its factorization.

21001120202021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130848390.

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

Adding to 21001120202021 its reverse (12020202110012), we get a palindrome (33021322312033).

The spelling of 21001120202021 in words is "twenty-one trillion, one billion, one hundred twenty million, two hundred two thousand, twenty-one".