21504135445 has 12 divisors (see below), whose sum is σ = 27942652836. Its totient is φ = 15879976320.

The previous prime is 21504135371. The next prime is 21504135449. The reversal of 21504135445 is 54453140512.

It can be written as a sum of positive squares in 6 ways, for example, as 4657653009 + 16846482436 = 68247^2 + 129794^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21504135445 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 21504135445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21504135449) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12723496 + ... + 12725185.

It is an arithmetic number, because the mean of its divisors is an integer number (2328554403).

Almost surely, 2^21504135445 is an apocalyptic number.

It is an amenable number.

21504135445 is a deficient number, since it is larger than the sum of its proper divisors (6438517391).

21504135445 is a wasteful number, since it uses less digits than its factorization.

21504135445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25448712 (or 25448699 counting only the distinct ones).

The product of its (nonzero) digits is 48000, while the sum is 34.

Adding to 21504135445 its reverse (54453140512), we get a palindrome (75957275957).

The spelling of 21504135445 in words is "twenty-one billion, five hundred four million, one hundred thirty-five thousand, four hundred forty-five".