16720805845 has 4 divisors (see below), whose sum is σ = 20064967020. Its totient is φ = 13376644672.

The previous prime is 16720805837. The next prime is 16720805867. The reversal of 16720805845 is 54850802761.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54850802761 = 79 ⋅694313959.

It can be written as a sum of positive squares in 2 ways, for example, as 9979410609 + 6741395236 = 99897^2 + 82106^2 .

It is a cyclic number.

It is not a de Polignac number, because 16720805845 - 2³ = 16720805837 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 16720805795 and 16720805804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1672080580 + ... + 1672080589.

It is an arithmetic number, because the mean of its divisors is an integer number (5016241755).

Almost surely, 2^16720805845 is an apocalyptic number.

It is an amenable number.

16720805845 is a deficient number, since it is larger than the sum of its proper divisors (3344161175).

16720805845 is an equidigital number, since it uses as much as digits as its factorization.

16720805845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3344161174.

The product of its (nonzero) digits is 537600, while the sum is 46.

The spelling of 16720805845 in words is "sixteen billion, seven hundred twenty million, eight hundred five thousand, eight hundred forty-five".