21705580611 has 56 divisors (see below), whose sum is σ = 38233087536. Its totient is φ = 12142923840.

The previous prime is 21705580609. The next prime is 21705580657. The reversal of 21705580611 is 11608550712.

21705580611 is a `hidden beast` number, since 2 + 1 + 70 + 5 + 580 + 6 + 1 + 1 = 666.

It is not a de Polignac number, because 21705580611 - 2¹ = 21705580609 is a prime.

It is a super-2 number, since 2×21705580611² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21705580111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 141 + ... + 208353.

It is an arithmetic number, because the mean of its divisors is an integer number (682733706).

Almost surely, 2^21705580611 is an apocalyptic number.

21705580611 is a deficient number, since it is larger than the sum of its proper divisors (16527506925).

21705580611 is a wasteful number, since it uses less digits than its factorization.

21705580611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208255 (or 208240 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 36.

The spelling of 21705580611 in words is "twenty-one billion, seven hundred five million, five hundred eighty thousand, six hundred eleven".