21723556305 has 16 divisors (see below), whose sum is σ = 37917480384. Its totient is φ = 10532633280.

The previous prime is 21723556297. The next prime is 21723556343. The reversal of 21723556305 is 50365532712.

It is not a de Polignac number, because 21723556305 - 2³ = 21723556297 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 65828794 + ... + 65829123.

It is an arithmetic number, because the mean of its divisors is an integer number (2369842524).

Almost surely, 2^21723556305 is an apocalyptic number.

It is an amenable number.

21723556305 is a deficient number, since it is larger than the sum of its proper divisors (16193924079).

21723556305 is a wasteful number, since it uses less digits than its factorization.

21723556305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131657936.

The product of its (nonzero) digits is 189000, while the sum is 39.

The spelling of 21723556305 in words is "twenty-one billion, seven hundred twenty-three million, five hundred fifty-six thousand, three hundred five".