21245240513 has 24 divisors (see below), whose sum is σ = 24978125952. Its totient is φ = 18015830784.

The previous prime is 21245240479. The next prime is 21245240521. The reversal of 21245240513 is 31504254212.

It is not a de Polignac number, because 21245240513 - 2⁸ = 21245240257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21245240113) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10178756 + ... + 10180842.

It is an arithmetic number, because the mean of its divisors is an integer number (1040755248).

Almost surely, 2^21245240513 is an apocalyptic number.

It is an amenable number.

21245240513 is a deficient number, since it is larger than the sum of its proper divisors (3732885439).

21245240513 is a wasteful number, since it uses less digits than its factorization.

21245240513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4221 (or 4214 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 29.

Adding to 21245240513 its reverse (31504254212), we get a palindrome (52749494725).

The spelling of 21245240513 in words is "twenty-one billion, two hundred forty-five million, two hundred forty thousand, five hundred thirteen".