20641623643 has 4 divisors (see below), whose sum is σ = 20720109168. Its totient is φ = 20563138120.

The previous prime is 20641623623. The next prime is 20641623647. The reversal of 20641623643 is 34632614602.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34632614602 = 2 ⋅17316307301.

It is a cyclic number.

It is not a de Polignac number, because 20641623643 - 2³³ = 12051689051 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20641623647) by changing a digit.

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, 39242368 + ... + 39242893.

It is an arithmetic number, because the mean of its divisors is an integer number (5180027292).

Almost surely, 2^20641623643 is an apocalyptic number.

20641623643 is a deficient number, since it is larger than the sum of its proper divisors (78485525).

20641623643 is an equidigital number, since it uses as much as digits as its factorization.

20641623643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78485524.

The product of its (nonzero) digits is 124416, while the sum is 37.

The spelling of 20641623643 in words is "twenty billion, six hundred forty-one million, six hundred twenty-three thousand, six hundred forty-three".