20172811 has 4 divisors (see below), whose sum is σ = 20184472. Its totient is φ = 20161152.

The previous prime is 20172797. The next prime is 20172827. The reversal of 20172811 is 11827102.

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.

It is a cyclic number.

It is not a de Polignac number, because 20172811 - 2⁷ = 20172683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20172211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2661 + ... + 6886.

It is an arithmetic number, because the mean of its divisors is an integer number (5046118).

Almost surely, 2^20172811 is an apocalyptic number.

20172811 is a deficient number, since it is larger than the sum of its proper divisors (11661).

20172811 is an equidigital number, since it uses as much as digits as its factorization.

20172811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11660.

The product of its (nonzero) digits is 224, while the sum is 22.

The square root of 20172811 is about 4491.4152557963. The cubic root of 20172811 is about 272.2213227113.

Adding to 20172811 its reverse (11827102), we get a palindrome (31999913).

The spelling of 20172811 in words is "twenty million, one hundred seventy-two thousand, eight hundred eleven".