20641853845 has 4 divisors (see below), whose sum is σ = 24770224620. Its totient is φ = 16513483072.

The previous prime is 20641853819. The next prime is 20641853851. The reversal of 20641853845 is 54835814602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54835814602 = 2 ⋅27417907301.

It can be written as a sum of positive squares in 2 ways, for example, as 4005497521 + 16636356324 = 63289^2 + 128982^2 .

It is a cyclic number.

It is not a de Polignac number, because 20641853845 - 2⁷ = 20641853717 is a prime.

It is a super-2 number, since 2×20641853845² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20641853795 and 20641853804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2064185380 + ... + 2064185389.

It is an arithmetic number, because the mean of its divisors is an integer number (6192556155).

Almost surely, 2^20641853845 is an apocalyptic number.

It is an amenable number.

20641853845 is a deficient number, since it is larger than the sum of its proper divisors (4128370775).

20641853845 is an equidigital number, since it uses as much as digits as its factorization.

20641853845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4128370774.

The product of its (nonzero) digits is 921600, while the sum is 46.

The spelling of 20641853845 in words is "twenty billion, six hundred forty-one million, eight hundred fifty-three thousand, eight hundred forty-five".