20945477591 has 4 divisors (see below), whose sum is σ = 20948982072. Its totient is φ = 20941973112.

The previous prime is 20945477569. The next prime is 20945477603. The reversal of 20945477591 is 19577454902.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20945477591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20945477561) 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, 1743260 + ... + 1755233.

It is an arithmetic number, because the mean of its divisors is an integer number (5237245518).

Almost surely, 2^20945477591 is an apocalyptic number.

20945477591 is a deficient number, since it is larger than the sum of its proper divisors (3504481).

20945477591 is an equidigital number, since it uses as much as digits as its factorization.

20945477591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3504480.

The product of its (nonzero) digits is 3175200, while the sum is 53.

The spelling of 20945477591 in words is "twenty billion, nine hundred forty-five million, four hundred seventy-seven thousand, five hundred ninety-one".