20643275605 has 4 divisors (see below), whose sum is σ = 24771930732. Its totient is φ = 16514620480.

The previous prime is 20643275603. The next prime is 20643275621. The reversal of 20643275605 is 50657234602.

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 7018083076 + 13625192529 = 83774^2 + 116727^2 .

It is not a de Polignac number, because 20643275605 - 2¹ = 20643275603 is a prime.

It is a super-2 number, since 2×20643275605² (a number of 21 digits) contains 22 as substring.

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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20643275603) 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, 2064327556 + ... + 2064327565.

It is an arithmetic number, because the mean of its divisors is an integer number (6192982683).

Almost surely, 2^20643275605 is an apocalyptic number.

It is an amenable number.

20643275605 is a deficient number, since it is larger than the sum of its proper divisors (4128655127).

20643275605 is an equidigital number, since it uses as much as digits as its factorization.

20643275605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4128655126.

The product of its (nonzero) digits is 302400, while the sum is 40.

The spelling of 20643275605 in words is "twenty billion, six hundred forty-three million, two hundred seventy-five thousand, six hundred five".