21243525211 has 4 divisors (see below), whose sum is σ = 21243863592. Its totient is φ = 21243186832.

The previous prime is 21243525209. The next prime is 21243525271. The reversal of 21243525211 is 11252534212.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21243525211 - 2¹ = 21243525209 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21243525211.

It is not an unprimeable number, because it can be changed into a prime (21243525271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44281 + ... + 210826.

It is an arithmetic number, because the mean of its divisors is an integer number (5310965898).

Almost surely, 2^21243525211 is an apocalyptic number.

21243525211 is a deficient number, since it is larger than the sum of its proper divisors (338381).

21243525211 is an equidigital number, since it uses as much as digits as its factorization.

21243525211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 338380.

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

Subtracting from 21243525211 its reverse (11252534212), we obtain a palindrome (9990990999).

The spelling of 21243525211 in words is "twenty-one billion, two hundred forty-three million, five hundred twenty-five thousand, two hundred eleven".