21521504305 has 32 divisors (see below), whose sum is σ = 29701778688. Its totient is φ = 14664499200.

The previous prime is 21521504293. The next prime is 21521504311. The reversal of 21521504305 is 50340512512.

It is not a de Polignac number, because 21521504305 - 2²¹ = 21519407153 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10340865 + ... + 10342945.

It is an arithmetic number, because the mean of its divisors is an integer number (928180584).

Almost surely, 2^21521504305 is an apocalyptic number.

It is an amenable number.

21521504305 is a deficient number, since it is larger than the sum of its proper divisors (8180274383).

21521504305 is a wasteful number, since it uses less digits than its factorization.

21521504305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3817.

The product of its (nonzero) digits is 6000, while the sum is 28.

The spelling of 21521504305 in words is "twenty-one billion, five hundred twenty-one million, five hundred four thousand, three hundred five".