20806811 has 4 divisors (see below), whose sum is σ = 20816400. Its totient is φ = 20797224.

The previous prime is 20806801. The next prime is 20806817. The reversal of 20806811 is 11860802.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 11860802 = 2 ⋅5930401.

It is a cyclic number.

It is not a de Polignac number, because 20806811 - 2¹⁰ = 20805787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20806817) 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, 185 + ... + 6453.

It is an arithmetic number, because the mean of its divisors is an integer number (5204100).

Almost surely, 2^20806811 is an apocalyptic number.

20806811 is a deficient number, since it is larger than the sum of its proper divisors (9589).

20806811 is an equidigital number, since it uses as much as digits as its factorization.

20806811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9588.

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 20806811 is about 4561.4483445502. The cubic root of 20806811 is about 275.0437880686.

The spelling of 20806811 in words is "twenty million, eight hundred six thousand, eight hundred eleven".