21033234521 has 12 divisors (see below), whose sum is σ = 23561004780. Its totient is φ = 18745796160.

The previous prime is 21033234487. The next prime is 21033234529. The reversal of 21033234521 is 12543233012.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 3033255625 + 17999978896 = 55075^2 + 134164^2 .

It is not a de Polignac number, because 21033234521 - 2³⁰ = 19959492697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21033234529) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2140910 + ... + 2150711.

It is an arithmetic number, because the mean of its divisors is an integer number (1963417065).

Almost surely, 2^21033234521 is an apocalyptic number.

It is an amenable number.

21033234521 is a deficient number, since it is larger than the sum of its proper divisors (2527770259).

21033234521 is a wasteful number, since it uses less digits than its factorization.

21033234521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4291676 (or 4291663 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 26.

Adding to 21033234521 its reverse (12543233012), we get a palindrome (33576467533).

The spelling of 21033234521 in words is "twenty-one billion, thirty-three million, two hundred thirty-four thousand, five hundred twenty-one".