20535721673 has 4 divisors (see below), whose sum is σ = 20536601988. Its totient is φ = 20534841360.

The previous prime is 20535721669. The next prime is 20535721751. The reversal of 20535721673 is 37612753502.

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 1701727504 + 18833994169 = 41252^2 + 137237^2 .

It is a cyclic number.

It is not a de Polignac number, because 20535721673 - 2² = 20535721669 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20535721673.

It is not an unprimeable number, because it can be changed into a prime (20535727673) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 404186 + ... + 452147.

It is an arithmetic number, because the mean of its divisors is an integer number (5134150497).

Almost surely, 2^20535721673 is an apocalyptic number.

It is an amenable number.

20535721673 is a deficient number, since it is larger than the sum of its proper divisors (880315).

20535721673 is an equidigital number, since it uses as much as digits as its factorization.

20535721673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 880314.

The product of its (nonzero) digits is 264600, while the sum is 41.

The spelling of 20535721673 in words is "twenty billion, five hundred thirty-five million, seven hundred twenty-one thousand, six hundred seventy-three".