21303332521 has 2 divisors, whose sum is σ = 21303332522. Its totient is φ = 21303332520.

The previous prime is 21303332509. The next prime is 21303332569. The reversal of 21303332521 is 12523330312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12263126121 + 9040206400 = 110739^2 + 95080^2 .

It is a cyclic number.

It is not a de Polignac number, because 21303332521 - 2⁵ = 21303332489 is a prime.

It is not a weakly prime, because it can be changed into another prime (21303332581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651666260 + 10651666261.

It is an arithmetic number, because the mean of its divisors is an integer number (10651666261).

Almost surely, 2^21303332521 is an apocalyptic number.

It is an amenable number.

21303332521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21303332521 is an equidigital number, since it uses as much as digits as its factorization.

21303332521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 25.

Adding to 21303332521 its reverse (12523330312), we get a palindrome (33826662833).

The spelling of 21303332521 in words is "twenty-one billion, three hundred three million, three hundred thirty-two thousand, five hundred twenty-one".