21531522241 has 4 divisors (see below), whose sum is σ = 21548762500. Its totient is φ = 21514281984.

The previous prime is 21531522167. The next prime is 21531522269. The reversal of 21531522241 is 14222513512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6891490225 + 14640032016 = 83015^2 + 120996^2 .

It is a cyclic number.

It is not a de Polignac number, because 21531522241 - 2³³ = 12941587649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21531522281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8618256 + ... + 8620753.

It is an arithmetic number, because the mean of its divisors is an integer number (5387190625).

Almost surely, 2^21531522241 is an apocalyptic number.

It is an amenable number.

21531522241 is a deficient number, since it is larger than the sum of its proper divisors (17240259).

21531522241 is a wasteful number, since it uses less digits than its factorization.

21531522241 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17240258.

The product of its digits is 4800, while the sum is 28.

The spelling of 21531522241 in words is "twenty-one billion, five hundred thirty-one million, five hundred twenty-two thousand, two hundred forty-one".