21724043505 has 16 divisors (see below), whose sum is σ = 34761597120. Its totient is φ = 11585114048.

The previous prime is 21724043503. The next prime is 21724043533. The reversal of 21724043505 is 50534042712.

It is a cyclic number.

It is not a de Polignac number, because 21724043505 - 2¹ = 21724043503 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21724043503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 125014 + ... + 243056.

It is an arithmetic number, because the mean of its divisors is an integer number (2172599820).

Almost surely, 2^21724043505 is an apocalyptic number.

It is an amenable number.

21724043505 is a deficient number, since it is larger than the sum of its proper divisors (13037553615).

21724043505 is a wasteful number, since it uses less digits than its factorization.

21724043505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130320.

The product of its (nonzero) digits is 33600, while the sum is 33.

The spelling of 21724043505 in words is "twenty-one billion, seven hundred twenty-four million, forty-three thousand, five hundred five".