20811081 has 4 divisors (see below), whose sum is σ = 27748112. Its totient is φ = 13874052.

The previous prime is 20811079. The next prime is 20811101. The reversal of 20811081 is 18011802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20811081 - 2¹ = 20811079 is a prime.

It is a super-3 number, since 3×20811081³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20811031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3468511 + ... + 3468516.

It is an arithmetic number, because the mean of its divisors is an integer number (6937028).

Almost surely, 2^20811081 is an apocalyptic number.

It is an amenable number.

20811081 is a deficient number, since it is larger than the sum of its proper divisors (6937031).

20811081 is an equidigital number, since it uses as much as digits as its factorization.

20811081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6937030.

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

The square root of 20811081 is about 4561.9163736307. The cubic root of 20811081 is about 275.0626017261.

Adding to 20811081 its reverse (18011802), we get a palindrome (38822883).

The spelling of 20811081 in words is "twenty million, eight hundred eleven thousand, eighty-one".