21202018021 has 2 divisors, whose sum is σ = 21202018022. Its totient is φ = 21202018020.

The previous prime is 21202018003. The next prime is 21202018051. The reversal of 21202018021 is 12081020212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19185020100 + 2016997921 = 138510^2 + 44911^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202018021 - 2¹¹ = 21202015973 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21202018021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21202018051) 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 as a sum of consecutive naturals, namely, 10601009010 + 10601009011.

It is an arithmetic number, because the mean of its divisors is an integer number (10601009011).

Almost surely, 2^21202018021 is an apocalyptic number.

It is an amenable number.

21202018021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202018021 is an equidigital number, since it uses as much as digits as its factorization.

21202018021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21202018021 its reverse (12081020212), we get a palindrome (33283038233).

The spelling of 21202018021 in words is "twenty-one billion, two hundred two million, eighteen thousand, twenty-one".