21504309145 has 64 divisors (see below), whose sum is σ = 29255385600. Its totient is φ = 15039129600.

The previous prime is 21504309133. The next prime is 21504309161. The reversal of 21504309145 is 54190340512.

It is not a de Polignac number, because 21504309145 - 2¹³ = 21504300953 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21504309145.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 77632747 + ... + 77633023.

It is an arithmetic number, because the mean of its divisors is an integer number (457115400).

Almost surely, 2^21504309145 is an apocalyptic number.

It is an amenable number.

21504309145 is a deficient number, since it is larger than the sum of its proper divisors (7751076455).

21504309145 is a wasteful number, since it uses less digits than its factorization.

21504309145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 706.

The product of its (nonzero) digits is 21600, while the sum is 34.

Adding to 21504309145 its reverse (54190340512), we get a palindrome (75694649657).

The spelling of 21504309145 in words is "twenty-one billion, five hundred four million, three hundred nine thousand, one hundred forty-five".