20871805845 has 64 divisors (see below), whose sum is σ = 38608462080. Its totient is φ = 9515827200.

The previous prime is 20871805817. The next prime is 20871805873. The reversal of 20871805845 is 54850817802.

It is an interprime number because it is at equal distance from previous prime (20871805817) and next prime (20871805873).

It is not a de Polignac number, because 20871805845 - 2³² = 16576838549 is a prime.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 20871805794 and 20871805803.

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 3949605 + ... + 3954885.

It is an arithmetic number, because the mean of its divisors is an integer number (603257220).

Almost surely, 2^20871805845 is an apocalyptic number.

It is an amenable number.

20871805845 is a deficient number, since it is larger than the sum of its proper divisors (17736656235).

20871805845 is a wasteful number, since it uses less digits than its factorization.

20871805845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6726.

The product of its (nonzero) digits is 716800, while the sum is 48.

The spelling of 20871805845 in words is "twenty billion, eight hundred seventy-one million, eight hundred five thousand, eight hundred forty-five".