18121191 has 16 divisors (see below), whose sum is σ = 26438400. Its totient is φ = 10949120.

The previous prime is 18121163. The next prime is 18121211. The reversal of 18121191 is 19112181.

It is a cyclic number.

It is not a de Polignac number, because 18121191 - 2¹³ = 18112999 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18121151) 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 15 ways as a sum of consecutive naturals, for example, 14206 + ... + 15428.

It is an arithmetic number, because the mean of its divisors is an integer number (1652400).

Almost surely, 2^18121191 is an apocalyptic number.

18121191 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

18121191 is a deficient number, since it is larger than the sum of its proper divisors (8317209).

18121191 is a wasteful number, since it uses less digits than its factorization.

18121191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1686.

The product of its digits is 144, while the sum is 24.

The square root of 18121191 is about 4256.8992236134. The cubic root of 18121191 is about 262.6609914930.

It can be divided in two parts, 1812 and 1191, that added together give a palindrome (3003).

The spelling of 18121191 in words is "eighteen million, one hundred twenty-one thousand, one hundred ninety-one".