20687519705 has 4 divisors (see below), whose sum is σ = 24825023652. Its totient is φ = 16550015760.

The previous prime is 20687519683. The next prime is 20687519729. The reversal of 20687519705 is 50791578602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5720199424 + 14967320281 = 75632^2 + 122341^2 .

It is not a de Polignac number, because 20687519705 - 2²⁶ = 20620410841 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 (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2068751966 + ... + 2068751975.

It is an arithmetic number, because the mean of its divisors is an integer number (6206255913).

Almost surely, 2^20687519705 is an apocalyptic number.

It is an amenable number.

20687519705 is a deficient number, since it is larger than the sum of its proper divisors (4137503947).

20687519705 is an equidigital number, since it uses as much as digits as its factorization.

20687519705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4137503946.

The product of its (nonzero) digits is 1058400, while the sum is 50.

The spelling of 20687519705 in words is "twenty billion, six hundred eighty-seven million, five hundred nineteen thousand, seven hundred five".