21545404320505 has 16 divisors (see below), whose sum is σ = 27862721928720. Its totient is φ = 15899349454848.

The previous prime is 21545404320439. The next prime is 21545404320511. The reversal of 21545404320505 is 50502340454512.

It can be written as a sum of positive squares in 8 ways, for example, as 1263135475449 + 20282268845056 = 1123893^2 + 4503584^2 .

It is a cyclic number.

It is not a de Polignac number, because 21545404320505 - 2²⁹ = 21544867449593 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 115562040 + ... + 115748329.

It is an arithmetic number, because the mean of its divisors is an integer number (1741420120545).

Almost surely, 2^{21545404320505} is an apocalyptic number.

It is an amenable number.

21545404320505 is a deficient number, since it is larger than the sum of its proper divisors (6317317608215).

21545404320505 is a wasteful number, since it uses less digits than its factorization.

21545404320505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231311820.

The product of its (nonzero) digits is 480000, while the sum is 40.

The spelling of 21545404320505 in words is "twenty-one trillion, five hundred forty-five billion, four hundred four million, three hundred twenty thousand, five hundred five".