20445721771 has 4 divisors (see below), whose sum is σ = 20458888632. Its totient is φ = 20432554912.

The previous prime is 20445721757. The next prime is 20445721819. The reversal of 20445721771 is 17712754402.

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

It is a cyclic number.

It is not a de Polignac number, because 20445721771 - 2²⁵ = 20412167339 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20445722771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6581101 + ... + 6584206.

It is an arithmetic number, because the mean of its divisors is an integer number (5114722158).

Almost surely, 2^20445721771 is an apocalyptic number.

20445721771 is a deficient number, since it is larger than the sum of its proper divisors (13166861).

20445721771 is a wasteful number, since it uses less digits than its factorization.

20445721771 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13166860.

The product of its (nonzero) digits is 109760, while the sum is 40.

The spelling of 20445721771 in words is "twenty billion, four hundred forty-five million, seven hundred twenty-one thousand, seven hundred seventy-one".