20810811 has 16 divisors (see below), whose sum is σ = 31797504. Its totient is φ = 11859744.

The previous prime is 20810809. The next prime is 20810813. The reversal of 20810811 is 11801802.

It is an interprime number because it is at equal distance from previous prime (20810809) and next prime (20810813).

It is not a de Polignac number, because 20810811 - 2¹ = 20810809 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (20810813) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8185 + ... + 10421.

It is an arithmetic number, because the mean of its divisors is an integer number (1987344).

Almost surely, 2^20810811 is an apocalyptic number.

20810811 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20810811 is a deficient number, since it is larger than the sum of its proper divisors (10986693).

20810811 is a wasteful number, since it uses less digits than its factorization.

20810811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2690.

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 20810811 is about 4561.8867807082. The cubic root of 20810811 is about 275.0614121799.

Subtracting from 20810811 its reverse (11801802), we obtain a palindrome (9009009).

The spelling of 20810811 in words is "twenty million, eight hundred ten thousand, eight hundred eleven".