21523132021 has 2 divisors, whose sum is σ = 21523132022. Its totient is φ = 21523132020.

The previous prime is 21523131997. The next prime is 21523132039. The reversal of 21523132021 is 12023132512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19451880900 + 2071251121 = 139470^2 + 45511^2 .

It is a cyclic number.

It is not a de Polignac number, because 21523132021 - 2¹⁷ = 21523000949 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21523131983 and 21523132001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21523132051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10761566010 + 10761566011.

It is an arithmetic number, because the mean of its divisors is an integer number (10761566011).

Almost surely, 2^21523132021 is an apocalyptic number.

It is an amenable number.

21523132021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21523132021 is an equidigital number, since it uses as much as digits as its factorization.

21523132021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 22.

Adding to 21523132021 its reverse (12023132512), we get a palindrome (33546264533).

The spelling of 21523132021 in words is "twenty-one billion, five hundred twenty-three million, one hundred thirty-two thousand, twenty-one".