21531322205 has 24 divisors (see below), whose sum is σ = 27506482848. Its totient is φ = 16176597248.

The previous prime is 21531322193. The next prime is 21531322213. The reversal of 21531322205 is 50222313512.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21531322205 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 658862 + ... + 690768.

It is an arithmetic number, because the mean of its divisors is an integer number (1146103452).

Almost surely, 2^21531322205 is an apocalyptic number.

It is an amenable number.

21531322205 is a deficient number, since it is larger than the sum of its proper divisors (5975160643).

21531322205 is a wasteful number, since it uses less digits than its factorization.

21531322205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32413 (or 32396 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 26.

Adding to 21531322205 its reverse (50222313512), we get a palindrome (71753635717).

The spelling of 21531322205 in words is "twenty-one billion, five hundred thirty-one million, three hundred twenty-two thousand, two hundred five".