20643840001 has 4 divisors (see below), whose sum is σ = 20650796100. Its totient is φ = 20636883904.

The previous prime is 20643839981. The next prime is 20643840023. The reversal of 20643840001 is 10004834602.

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 6095861776 + 14547978225 = 78076^2 + 120615^2 .

It is a cyclic number.

It is not a de Polignac number, because 20643840001 - 2⁵ = 20643839969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20643840031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3473596 + ... + 3479533.

It is an arithmetic number, because the mean of its divisors is an integer number (5162699025).

It is a Proth number, since it is equal to 39375 ⋅ 2¹⁹ + 1 and 39375 < 2¹⁹.

Almost surely, 2^20643840001 is an apocalyptic number.

It is an amenable number.

20643840001 is a deficient number, since it is larger than the sum of its proper divisors (6956099).

20643840001 is an equidigital number, since it uses as much as digits as its factorization.

20643840001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6956098.

The product of its (nonzero) digits is 4608, while the sum is 28.

The spelling of 20643840001 in words is "twenty billion, six hundred forty-three million, eight hundred forty thousand, one".