21033131521 has 2 divisors, whose sum is σ = 21033131522. Its totient is φ = 21033131520.

The previous prime is 21033131507. The next prime is 21033131531. The reversal of 21033131521 is 12513133012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16522531600 + 4510599921 = 128540^2 + 67161^2 .

It is a cyclic number.

It is not a de Polignac number, because 21033131521 - 2⁵ = 21033131489 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21033131492 and 21033131501.

It is not a weakly prime, because it can be changed into another prime (21033131501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10516565760 + 10516565761.

It is an arithmetic number, because the mean of its divisors is an integer number (10516565761).

Almost surely, 2^21033131521 is an apocalyptic number.

It is an amenable number.

21033131521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033131521 is an equidigital number, since it uses as much as digits as its factorization.

21033131521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 22.

Adding to 21033131521 its reverse (12513133012), we get a palindrome (33546264533).

The spelling of 21033131521 in words is "twenty-one billion, thirty-three million, one hundred thirty-one thousand, five hundred twenty-one".