20639120641 has 4 divisors (see below), whose sum is σ = 20642996052. Its totient is φ = 20635245232.

The previous prime is 20639120617. The next prime is 20639120651. The reversal of 20639120641 is 14602193602.

It is a happy number.

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 11423120641 + 9216000000 = 106879^2 + 96000^2 .

It is a cyclic number.

It is not a de Polignac number, because 20639120641 - 2²³ = 20630732033 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20639120597 and 20639120606.

It is not an unprimeable number, because it can be changed into a prime (20639120611) 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, 1929706 + ... + 1940371.

It is an arithmetic number, because the mean of its divisors is an integer number (5160749013).

Almost surely, 2^20639120641 is an apocalyptic number.

It is an amenable number.

20639120641 is a deficient number, since it is larger than the sum of its proper divisors (3875411).

20639120641 is an equidigital number, since it uses as much as digits as its factorization.

20639120641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3875410.

The product of its (nonzero) digits is 15552, while the sum is 34.

The spelling of 20639120641 in words is "twenty billion, six hundred thirty-nine million, one hundred twenty thousand, six hundred forty-one".