20831091 has 16 divisors (see below), whose sum is σ = 28304640. Its totient is φ = 13625120.

The previous prime is 20831053. The next prime is 20831093. The reversal of 20831091 is 19013802.

It is a cyclic number.

It is not a de Polignac number, because 20831091 - 2¹⁰ = 20830067 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20831093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66826 + ... + 67136.

It is an arithmetic number, because the mean of its divisors is an integer number (1769040).

Almost surely, 2^20831091 is an apocalyptic number.

20831091 is a deficient number, since it is larger than the sum of its proper divisors (7473549).

20831091 is a wasteful number, since it uses less digits than its factorization.

20831091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 20831091 is about 4564.1090039569. The cubic root of 20831091 is about 275.1507316916.

Adding to 20831091 its reverse (19013802), we get a palindrome (39844893).

The spelling of 20831091 in words is "twenty million, eight hundred thirty-one thousand, ninety-one".