21533525310021 has 16 divisors (see below), whose sum is σ = 30400508141568. Its totient is φ = 13511126182400.

The previous prime is 21533525310001. The next prime is 21533525310067. The reversal of 21533525310021 is 12001352533512.

It is a cyclic number.

It is not a de Polignac number, because 21533525310021 - 2³⁷ = 21396086356549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533525310001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5235361 + ... + 8395001.

It is an arithmetic number, because the mean of its divisors is an integer number (1900031758848).

Almost surely, 2^{21533525310021} is an apocalyptic number.

It is an amenable number.

21533525310021 is a deficient number, since it is larger than the sum of its proper divisors (8866982831547).

21533525310021 is a wasteful number, since it uses less digits than its factorization.

21533525310021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3293292.

The product of its (nonzero) digits is 27000, while the sum is 33.

Adding to 21533525310021 its reverse (12001352533512), we get a palindrome (33534877843533).

The spelling of 21533525310021 in words is "twenty-one trillion, five hundred thirty-three billion, five hundred twenty-five million, three hundred ten thousand, twenty-one".