21243411245 has 24 divisors (see below), whose sum is σ = 29664386424. Its totient is φ = 14561842176.

The previous prime is 21243411227. The next prime is 21243411257. The reversal of 21243411245 is 54211434212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 7802718889 + 13440692356 = 88333^2 + 115934^2 .

It is not a de Polignac number, because 21243411245 - 2²⁴ = 21226634029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 774689 + ... + 801641.

It is an arithmetic number, because the mean of its divisors is an integer number (1236016101).

Almost surely, 2^21243411245 is an apocalyptic number.

It is an amenable number.

21243411245 is a deficient number, since it is larger than the sum of its proper divisors (8420975179).

21243411245 is a wasteful number, since it uses less digits than its factorization.

21243411245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30189 (or 30182 counting only the distinct ones).

The product of its digits is 7680, while the sum is 29.

Adding to 21243411245 its reverse (54211434212), we get a palindrome (75454845457).

The spelling of 21243411245 in words is "twenty-one billion, two hundred forty-three million, four hundred eleven thousand, two hundred forty-five".